Formulas
The formulas behind the so67 calculators, grouped by category, each linked to the calculator that applies it. Each formula is the one the calculator applies, as shown next to its result.
Financial
15 of 40 calculators shown- Bond Yield
y ≈ (C + (F − P) ÷ t) ÷ ((F + P) ÷ 2) - Budget Allocation
Aᵢ = B × pᵢ ÷ 100 - Certificate Of Deposit
A = P × (1 + r ÷ n)^(n × t) - Compound Interest
A = P(1 + r/n)^(nt) - Credit Card Payoff
Bₙ₊₁ = Bₙ × (1 + APR ÷ 12) − P - Debt Payoff
B = ΣPₘᵢₙ + E; Iₘ = Dₘ × r ÷ 12 - Dividend Growth
D_y = N × D₀ × (1 + g)^(y − 1) - Dollar Cost Averaging
Bₙ₊₁ = Bₙ × (1 + r ÷ f) + C - Emergency Fund
T = E × c; S = max(T − C, 0) / n - Inflation
F = P(1 + r)^t; PP = P/(1 + r)^t - Investment Return
G = E + W − I − C; ROI = G ÷ (I + C) × 100 - Line Of Credit Payment
Bₙ₊₁ = Bₙ + Iₙ + Dₙ − Pₙ - Loan
M = P[r(1+r)^n]/[(1+r)^n-1] - Net Worth
NW = ΣA − ΣL - Portfolio Rebalancing
ΔH = V × wₜ ÷ 100 − H₀
Health
15 of 40 calculators shown- Adjusted Body Weight
AdjBW = IBW + f × (AW − IBW) - Blood Volume Estimate
BV = c₁H³ + c₂W + c₀ - BMI
BMI = W / H²; BMI′ = BMI / 25; PI = W / H³ - BMR
BMR = 10W + 6.25H − 5A + 5 - Body Fat
%BF = 1.20 × BMI + 0.23 × A − 10.8 × S − 5.4; S ∈ {0,1} - Body Surface Area
BSA = √(H × W ÷ 3600) - Calorie
TDEE = (10W + 6.25H - 5A + 5) × F - Healthy Weight
Wmin = 18.5 × H² - Heart Rate Zones
HRₜ = (220 − A) × i - Hydration
Vₚ = Vᵣ + Vₑ - Ideal Body Weight
IBW = B + 2.3 × I - Lean Body Mass
LBM = W × (1 − BF ÷ 100) - Macronutrients
G = C × P / 100 / K - Pregnancy Due Date
EDD = LMP + 280 d - Pulse Pressure
PP = SBP − DBP; MAP ≈ DBP + PP ÷ 3
Real estate
15 of 40 calculators shown- Biweekly Mortgage
P₂w = Pₘ ÷ 2; f = 26/y - Cap Rate
CR = NOI ÷ V × 100 - Closing Costs
C = ΣF + Σ(P × r ÷ 100) - Down Payment
C = (T − P) ÷ n - Extra Mortgage Payment
Pₐ = Pₘ + Eₘ - Gross Rent Multiplier
GRM = P ÷ Rₐ - Home Equity
E = V − M − D - House Flip Profit
Π = S − P − R − H − F − Cₛ - Loan To Value
LTV = Lₛ ÷ V × 100 - Mortgage
M = P[r(1+r)^n]/[(1+r)^n-1] - Mortgage Affordability
L = min(I × GDS − H, I × TDS − D − H) × [1 − (1+r)^−n] ÷ r - Mortgage Amortization
M = P[r(1+r)^n] ÷ [(1+r)^n−1]; Mₐ = M + E - Mortgage Points
n_BE = Cₚ ÷ Sₘ - Mortgage Refinance
S = ΣP₀ − ΣP₁ − C - Property Tax
Tₐ = Vₐ × rₑ ÷ 100
Fitness and sports
15 of 40 calculators shown- Running Pace
pace = t ÷ d - Race Time Prediction
T₂ = T₁ × (D₂ ÷ D₁)^1.06 - Vo2max Cooper
VO₂max = (d − 504.9) ÷ 44.73 - Max Heart Rate
HRmax = 208 − 0.7 × age - Target Heart Rate
THR = HRrest + (HRmax − HRrest) × I - Calories Burned Met
kcal = MET × 3.5 × kg ÷ 200 × min - One Rep Max
1RM = w × (1 + r ÷ 30) - Training Load
load = RPE × minutes - Swimming Pace
pace = t × 100 ÷ d - Cycling Speed
v = d × 60 ÷ t - Power To Weight
P/W = watts ÷ kg - Steps To Distance
d = steps × stride ÷ 1000 - Rowing Split
split = t × 500 ÷ d - Heart Rate Reserve
HRR = HRmax − HRrest - Running Cadence
cadence = v × 1000 ÷ 60 ÷ stride
Home and garden
15 of 40 calculators shown- Garden Soil Volume
V = L × W × D - Mulch Coverage
V = A × d - Lawn Fertilizer
product = (A ÷ 100) × rate ÷ (N ÷ 100) - Grass Seed
seed = A × rate ÷ 1000 - Plant Spacing
n = A ÷ s² - Irrigation Water Need
V = A × mm - Compost Ratio
C:N = (Cb × Rb + Cg × Rg) ÷ (Cb + Cg) - Raised Bed Fill
V = L × W × H × n - Rain Barrel Capture
V = A × mm × e - Paint Coverage Room
L = (P × h − openings) × coats ÷ spread - Houseplant Watering
V = π r² × d × fraction - Flooring Planks
packs = A × (1 + waste) ÷ pack area - Wall Tile Count
n = A ÷ tile area × (1 + waste) - Firewood Cord
cords = L × H × W ÷ 3.6246 - Pool Volume
V = L × W × d × 1000
Education and study
15 of 40 calculators shown- GPA Calculator
GPA = Σ(g × c) ÷ Σc - Weighted Grade
grade = Σ(s × w) ÷ Σw - Final Exam Grade
needed = (target − current × (1 − w)) ÷ w - Test Score Percentage
score = correct ÷ total × 100 - Grade Curve
curved = raw + (target − mean) - Class Attendance
rate = attended ÷ held × 100 - Study Time Planner
hours per week = credits × ratio - Reading Speed
wpm = words ÷ minutes - Reading Time
minutes = words ÷ wpm - Typing Speed
net wpm = (chars ÷ 5 − errors) ÷ minutes - Words Per Page
pages = words ÷ words per page - Essay Word Count
section = total × share - Flashcard Review
daily = cards ÷ days × repetitions - Student Loan Payment
P = L × r ÷ (1 − (1 + r)^−n) - Tuition Savings
FV = P(1 + r)^n + C × ((1 + r)^n − 1) ÷ r
Media and photography
15 of 40 calculators shown- Shutter Exposure
t₂ = t₁ × 2^(EV₁ − EV₂) - Depth Of Field
DoF ≈ 2u²Nc ÷ f² - Field Of View
θ = 2 arctan(d ÷ 2f) - Hyperfocal Distance
H = f² ÷ (Nc) + f - Crop Factor
f_eq = f × crop - Print Resolution
PPI = pixels ÷ inches - Video File Size
size = bitrate × duration ÷ 8 - Bitrate Calculator
bitrate = size × 8 ÷ duration - Frame Rate Duration
frames = fps × seconds - Audio File Size
size = rate × depth × channels × seconds ÷ 8 - Color Contrast Ratio
ratio = (L₁ + 0.05) ÷ (L₂ + 0.05) - Image Resize
h₂ = w₂ × h₁ ÷ w₁ - Golden Ratio
a = L ÷ φ - Screen Size
w = d × r ÷ √(r² + 1) - Storage Duration
minutes = capacity × 8 ÷ bitrate
Pets and agriculture
15 of 40 calculators shown- Pet Food Portion
grams = (RER × factor) ÷ density × 1000 - Pet Age Conversion
human years = 16 ln(age) + 31 - Aquarium Heater Watts
W = V × ΔT × 0.25 - Litter Box Count
boxes = cats + 1 - Pet Medication Dose
volume = weight × dose ÷ concentration - Kennel Space
area = animals × area each - Chicken Feed
feed = birds × grams × days ÷ 1000 - Beehive Honey Yield
yield = hives × frames × kg per frame - Livestock Water
water = head × litres × days - Pasture Stocking Rate
rate = head ÷ hectares - Crop Seed Rate
seed = area × rate - Silage Tonnage
tonnes = V × density ÷ 1000 - Milk Yield
yield = cows × litres × days - Egg Production
rate = eggs ÷ (hens × days) × 100 - Feed Conversion Ratio
FCR = feed ÷ gain
Events and hospitality
15 of 40 calculators shown- Event Catering Quantity
total = guests × portion × servings - Party Drink Count
drinks = guests × per hour × hours - Wedding Budget Split
category = total × share - Guest Seating Tables
tables = guests ÷ seats per table - Venue Capacity
capacity = area ÷ area per person - Event Staff Ratio
staff = guests ÷ guests per staff - Cake Servings
servings = tier area ÷ slice area - Punch Recipe Scaling
batch = servings ÷ recipe servings × recipe volume - Table Linen Size
cloth = table + 2 × drop - Dance Floor Size
area = guests × share × area per dancer - Parking Space Need
spaces = guests ÷ occupancy - Event Timeline Buffer
total = segments × duration × (1 + buffer) - Photo Booth Throughput
sessions = hours × 60 ÷ minutes per session - Invitation Response Rate
rate = replies ÷ sent × 100 - Gift Registry Target
items = guests × ratio
Physics and engineering
15 of 40 calculators shown- Newtons Second Law
F = m × a - Kinetic Energy
Ek = ½ × m × v² - Potential Energy
Ep = m × g × h - Free Fall
d = ½ × g × t² - Projectile Range
R = v² × sin(2θ) ÷ g - Work Done
W = F × d × cos(θ) - Mechanical Power
P = W ÷ t - Hookes Law
F = k × x - Pressure Force Area
P = F ÷ A - Density Mass Volume
ρ = m ÷ V - Hydrostatic Pressure
P = ρ × g × h - Wave Speed
v = f × λ - Photon Energy
E = h × c ÷ λ - Ohms Law
V = I × R - Electrical Power
P = V × I
Chemistry
15 of 40 calculators shown- Molarity
c = n ÷ V - Molar Mass From Moles
m = n × M - Solution Dilution
M₁ × V₁ = M₂ × V₂ - Ideal Gas Law
n = (P × V) ÷ (R × T) - Percent Yield
% yield = (actual ÷ theoretical) × 100 - Percent Composition
% composition = (element mass ÷ compound mass) × 100 - Ph From Concentration
pH = −log₁₀[H⁺] - Poh Calculator
pOH = −log₁₀[OH⁻] - Henderson Hasselbalch
pH = pKa + log₁₀([A⁻] ÷ [HA]) - Solution Density
ρ = m ÷ V - Mass To Moles
n = m ÷ M - Moles To Particles
N = n × Nₐ - Gas Density Stp
ρ = M ÷ Vm (Vm = 22.414 L/mol at 0 °C, 1 atm) - Combined Gas Law
(P₁ × V₁) ÷ T₁ = (P₂ × V₂) ÷ T₂ - Boyles Law
P₁ × V₁ = P₂ × V₂
Mathematics
15 of 40 calculators shown- Circle Area
A = π × r² - Sphere Volume
V = 4⁄3 × π × r³ - Cylinder Volume
V = π × r² × h - Cone Volume
V = (π × r² × h) ÷ 3 - Triangle Area Heron
A = √(s × (s − a) × (s − b) × (s − c)), s = (a + b + c) ÷ 2 - Pythagoras Hypotenuse
c = √(a² + b²) - Box Volume
V = l × w × h - Trapezoid Area
A = ((a + b) ÷ 2) × h - Ellipse Area
A = π × a × b - Regular Polygon Area
A = (n × s²) ÷ (4 × tan(π ÷ n)) - Arc Sector
L = r × θ (θ in radians), A = ½ × r² × θ - Distance Two Points
d = √((x₂ − x₁)² + (y₂ − y₁)²) - Line Slope
m = (y₂ − y₁) ÷ (x₂ − x₁) - Quadratic Discriminant
Δ = b² − 4 × a × c - Arithmetic Sequence
aₙ = a₁ + (n − 1) × d, Sₙ = (n ÷ 2) × (a₁ + aₙ)
Business and marketing
15 of 40 calculators shown- Break Even Point
Break-even units = Fixed costs ÷ (Price − Variable cost) - Gross Margin
Gross margin % = (Revenue − COGS) ÷ Revenue × 100 - Markup Vs Margin
Price = Cost × (1 + Markup%); Margin% = (Price − Cost) ÷ Price × 100 - Profit Margin
Net profit margin % = Net income ÷ Revenue × 100 - ROI Calculator
ROI % = (Final value − Cost) ÷ Cost × 100 - Customer Acquisition Cost
CAC = Sales and marketing spend ÷ New customers acquired - Customer Lifetime Value
CLV = AOV × Purchase frequency × Lifespan × Gross margin% - Churn Rate
Churn rate % = Customers lost ÷ Customers at start × 100 - Conversion Rate
Conversion rate % = Conversions ÷ Visitors × 100 - Cost Per Click
CPC = Ad spend ÷ Clicks - Cost Per Mille
CPM = Ad spend ÷ Impressions × 1000 - Click Through Rate
CTR % = Clicks ÷ Impressions × 100 - Return On Ad Spend
ROAS = Revenue from ads ÷ Ad spend - Average Order Value
AOV = Total revenue ÷ Number of orders - Inventory Turnover
Inventory turnover = COGS ÷ Average inventory
Construction and trades
15 of 40 calculators shown- Concrete Slab Volume
V = L × W × t, then V × (1 + waste ÷ 100) - Concrete Bags Needed
bags = V(m³) × 1000 × (1 + waste ÷ 100) ÷ yield per bag (L) - Rebar Spacing Count
n = floor(span ÷ spacing) + 1, both directions - Mortar Brickwork
mortar = area × rate per m² × (1 + waste ÷ 100) - Brick Count Wall
bricks = area ÷ ((L + joint) × (H + joint)), plus waste - Block Count Wall
blocks = area ÷ ((L + joint) × (H + joint)), plus waste - Drywall Sheets
sheets = area ÷ (sheet L × sheet W) × (1 + waste ÷ 100) - Wall Stud Count
studs = floor(wall length ÷ spacing) + 1 - Roof Pitch Angle
θ = atan(rise ÷ 12); slope factor = √(1 + (rise ÷ 12)²) - Roof Area Pitch
A = footprint area × √(1 + (rise ÷ run)²) - Shingle Bundles
bundles = roof area ÷ coverage per bundle × (1 + waste ÷ 100) - Excavation Volume
V = L × W × D, then V × (1 + bulking ÷ 100) - Gravel Tonnage
t = area × depth × bulk density ÷ 1000 - Asphalt Tonnage
t = L × W × thickness × density ÷ 1000 - Paint Coverage Surface
L = area × coats ÷ spreading rate
Cooking and food
15 of 40 calculators shown- Recipe Scaling Factor
factor = desired servings ÷ original servings - Servings Per Batch
servings = total yield ÷ portion weight - Bakers Percentage Hydration
hydration % = water ÷ flour × 100 (baker's percentage) - Sourdough Starter Ratio
1 : f : w — flour = starter × f, water = starter × w - Bread Dough Total Flour
levain flour = levain ÷ (1 + hydration ÷ 100); total flour = added flour + levain flour - Yeast Conversion
active dry = fresh ÷ 2.5; instant = fresh ÷ 3 (standard yeast equivalence) - Roast Cooking Time
oven time = weight (kg) × stated rate (min/kg); total = oven time + resting - Turkey Thawing Time
thawing time = weight (kg) × stated rate (h/kg) - Brine Salt Ratio
salt (g) = water (L) × 1000 × salt % ÷ 100 - Sugar Syrup Ratio
sugar = total × sugar parts ÷ (sugar parts + water parts) - Coffee Brew Ratio
water (g) = coffee (g) × ratio n, for a 1 : n brew ratio - Espresso Yield Ratio
brew ratio = liquid yield ÷ dry dose (spent puck retains about 2 g water per g of dose) - Tea Steeping Water
water = cups × cup volume; leaves = cups × leaves per cup - Cocktail Dilution
dilution water = base volume × dilution % ÷ 100 - Food Cost Per Serving
cost per serving = total ingredient cost ÷ servings
Automotive and transport
15 of 40 calculators shown- Fuel Consumption L100km
L/100 km = litres × 100 ÷ distance (km) - Miles Per Gallon
MPG = miles ÷ gallons - Fuel Cost Per Trip
Cost = distance ÷ 100 × L/100 km × price per litre - Fuel Cost Per Year
Annual cost = km/year ÷ 100 × L/100 km × price per litre - Engine Displacement
V = π ÷ 4 × bore² × stroke × cylinders - Compression Ratio
CR = (Vs + Vc) ÷ Vc - Horsepower From Torque
hp = torque (lb·ft) × rpm ÷ 5252 - Torque From Horsepower
torque (lb·ft) = hp × 5252 ÷ rpm - Speed From RPM
v = rpm ÷ (gear × final drive) × π × d × 60 ÷ 1000 - Gear Ratio
ratio = driven teeth ÷ drive teeth - Tyre Circumference
d = rim × 25.4 + 2 × width × aspect ÷ 100; C = π × d - Tyre Speed Rating Distance
d = v × t - Zero To Sixty Estimate
t = ½ × m × v² ÷ P (v = 60 mph = 26.8224 m/s) - Braking Distance
d = v² ÷ (2 × μ × g) - Stopping Distance
d = v × t_reaction + v² ÷ (2 × μ × g)
Statistics and probability
15 of 40 calculators shown- Mean Of Range
mean = (a + b) / 2, n = b − a + 1, sum = n × (a + b) / 2 - Standard Deviation From Variance
σ = √(σ²) - Variance From Standard Deviation
σ² = σ × σ - Z Score
z = (x − μ) / σ - Standard Error Mean
SE = σ / √n - Margin Of Error
E = z × σ / √n - Sample Size Proportion
n = z² × p × (1 − p) / E² - Coefficient Of Variation
CV = σ / μ × 100 - Percentage Change
%Δ = (new − old) / old × 100 - Percentage Of Total
% = part / total × 100 - Odds From Probability
odds for = p / (1 − p), odds against = (1 − p) / p - Probability From Odds
p = a / (a + b) - Binomial Probability
P(X = k) = C(n, k) × p^k × (1 − p)^(n − k) - Expected Value
EV = p × gain − (1 − p) × loss - Combinations
C(n, k) = n! / (k! × (n − k)!)
Technology and computing
15 of 40 calculators shown- Data Transfer Time
t = (size_GB × 1000 × 8) ÷ (bandwidth_Mbps × efficiency) - Download Time
t = (size_MB × 8) ÷ speed_Mbps - Streaming Bandwidth
BW = bitrate × viewers × (1 + overhead) - Video Storage Size
size_MB = bitrate_Mbps × minutes × 60 ÷ 8 - Photo Storage Size
size_MB = photos × average_MB - Raid Usable Capacity
usable = (disks − parity) × disk_size - Backup Window Throughput
rate_MB/s = size_GB × 1000 ÷ (hours × 3600) - Uptime Availability
downtime = (1 − availability) × period - Downtime Per Year
availability = (1 − downtime ÷ 525600) × 100 - Requests Per Second
RPS = requests_per_day ÷ 86400 - Server Cost Per Request
cost/request = monthly_cost ÷ monthly_requests - Bytes To Gigabytes
GB = bytes ÷ 1 000 000 000 ; GiB = bytes ÷ 1 073 741 824 - Video Bitrate Resolution
bitrate = width × height × fps × bits_per_pixel - Password Entropy
H = length × log2(charset_size) - Brute Force Time
t = 2^H ÷ 2 ÷ guesses_per_second
Travel and navigation
15 of 40 calculators shown- Trip Duration
t = d ÷ v - Average Speed
v = d ÷ t - Arrival Time
arrival = (departure + duration + Δtz) mod 24 - Time Zone Difference
Δt = UTC_destination − UTC_origin - Jet Lag
days = zones × (2 ÷ 3) - Flight Time
t = d ÷ v_cruise + t_ground - Great Circle Distance
d = 2R × asin(√(sin²(Δφ÷2) + cosφ₁ × cosφ₂ × sin²(Δλ÷2))) - Road Trip Fuel
L = d × (consumption ÷ 100); cost = L × price - Trip Cost Split
share = total ÷ people - Daily Travel Budget
daily = budget ÷ days - Hotel Cost Per Person
rate = total ÷ nights ÷ people - Currency Conversion
target = amount × rate; net = target × (1 − fee ÷ 100) - Tip Amount
tip = bill × (p ÷ 100); total = bill + tip - Per Diem Total
total = (meals + lodging) × days - Baggage Overage Fee
fee = max(0, weight − allowance) × rate
Energy and environment
15 of 40 calculators shown- Appliance Energy Cost
kWh/year = (W × h/day × days/year) ÷ 1000; cost = kWh × price - Kwh From Watts
E(kWh) = P(W) × t(h) ÷ 1000 - Solar Panel Output
E/day = (Wp × n ÷ 1000) × PSH × derate - Solar Array Size
kW = daily kWh ÷ (PSH × derate) - Solar Payback
Payback = (cost − incentives) ÷ (annual kWh × price) - Battery Capacity Kwh
E(kWh) = V × Ah ÷ 1000; usable = E × DoD - Battery Runtime
t(h) = (kWh × DoD × η) ÷ (load W ÷ 1000) - Inverter Sizing
P_dc = P_ac ÷ η; I_dc = P_dc ÷ V_bus; surge = P_ac × factor - Generator Fuel Consumption
Fuel(L) = kW_rated × load factor × hours × SFC - Heat Pump Cop
Q_out = P_in × COP - Heating Degree Days
HDD = ΔT × days; E = HDD × K - Wall Heat Loss
Q = U × A × ΔT; R = 1 ÷ U - Water Heating Energy
Q = m × c × ΔT (c = 4186 J/kg·K, 1 L ≈ 1 kg); input = Q ÷ η - Electricity Carbon Footprint
CO₂(kg) = kWh × intensity(g/kWh) ÷ 1000 - Carbon Offset Trees
Trees = annual CO₂(kg) ÷ sequestration per tree (kg/year)
Tax and payroll
15 of 40 calculators shown- Gross To Net Pay
net = gross − gross × rate ÷ 100 - Hourly To Annual Salary
annual = hourly × hours per week × weeks per year - Annual To Hourly Rate
hourly = annual ÷ (hours per week × weeks per year) - Overtime Pay
overtime pay = hourly × multiplier × overtime hours - Time And A Half Total
total = rate × regular hours + rate × multiplier × overtime hours - Salary After Raise
new salary = salary × (1 + raise ÷ 100) - Pay Per Pay Period
pay per period = annual salary ÷ pay periods per year - Prorated Salary
prorated = annual salary × months worked ÷ 12 - Vat Added
gross = net × (1 + VAT rate ÷ 100) - Vat Removed
net = gross ÷ (1 + VAT rate ÷ 100) - Sales Tax On Purchase
tax = amount × rate ÷ 100 - Effective Tax Rate
effective rate = tax paid ÷ total income × 100 - Marginal Vs Effective
gap = marginal rate − (tax paid ÷ income × 100) - Self Employment Set Aside
quarterly = profit × rate ÷ 100 ÷ 4 - Employer Payroll Cost
employer cost = gross × (1 + contribution rate ÷ 100)
Biology and lab
15 of 40 calculators shown- Cell Density Haemocytometer
cells/mL = (cells counted ÷ squares counted) × dilution factor × 10⁴ - Dilution Factor
DF = V_final ÷ V_stock - Serial Dilution Final Concentration
C_n = C₀ ÷ DF^n - Colony Forming Units
CFU/mL = colonies ÷ (volume plated × dilution factor) - Doubling Time Growth Rate
td = ln(2) ÷ µ - Exponential Population Growth
N = N₀ × e^(µ × t) - Bacterial Generation Time
n = log₂(N ÷ N₀) ; g = t ÷ n - Dna Concentration A260
C (µg/mL) = A260 × 50 × dilution factor (dsDNA, 1 cm path) - Protein Concentration A280
C (mg/mL) = A280 × dilution ÷ ε(0.1 %) - Beer Lambert Concentration
c = A ÷ (ε × l) - Primer Melting Temperature
Tm = 2 × (A + T) + 4 × (G + C) (Wallace rule, short primers) - Gc Content Percentage
GC % = (G + C) ÷ (A + T + G + C) × 100 - Dna Molecular Weight
MW = bp × 617.96 + 36.04 g/mol (sodium-salt dsDNA) - Rna To Protein Length
residues = nucleotides ÷ 3 ; MW ≈ residues × 110 Da - Enzyme Specific Activity
specific activity = total units ÷ total protein (mg)
Time and date
15 of 40 calculators shown- Hours Between Times
duration = end − start (+24 h if the span crosses midnight) - Minutes To Hours Minutes
h = minutes ÷ 60; remainder = minutes − 60 × ⌊h⌋ - Days To Time Units
hours = days × 24; minutes = days × 1440; seconds = days × 86 400 - Weeks Between Days
weeks = days ÷ 7; remainder = days − 7 × ⌊weeks⌋ - Working Days From Total
working days = total days × (7 − days off per week) ÷ 7 - Hours Per Week To Year
annual hours = hours per week × weeks worked per year - Age In Days
days = years × 365 (common year) - Seconds Duration Breakdown
d = ⌊s ÷ 86 400⌋; h = ⌊(s − 86 400d) ÷ 3600⌋; m = ⌊(s − 86 400d − 3600h) ÷ 60⌋ - Milliseconds To Seconds
seconds = milliseconds ÷ 1000 - Time Card Daily Total
paid hours = (clock-out − clock-in) − break minutes ÷ 60 - Break Adjusted Shift
worked hours = shift hours − break minutes ÷ 60 - Overtime Hours
overtime = max(0, hours worked − threshold) - Meeting Cost
cost = attendees × hourly rate × (minutes ÷ 60) - Project Working Days
working days = calendar days × working days per week ÷ 7 - Deadline Days Remaining
elapsed % = days elapsed ÷ (elapsed + remaining) × 100
Unit conversions
15 of 40 calculators shown- Length Metric To Imperial
in = m ÷ 0.0254 (1 in = 25.4 mm exactly) - Distance Km To Miles
mi = km × 1000 ÷ 1609.344 - Weight Kg To Pounds
lb = kg ÷ 0.45359237 (exact) - Mass Grams To Ounces
oz = g ÷ 28.349523125 (1 lb = 453.59237 g exactly) - Temperature Celsius To Fahrenheit
°F = °C × 9/5 + 32 ; K = °C + 273.15 - Temperature Fahrenheit To Celsius
°C = (°F − 32) × 5/9 - Volume Litres To Gallons
US gal = L ÷ 3.785411784 ; imp gal = L ÷ 4.54609 - Volume Millilitres To Cups
US cup = mL ÷ 236.5882365 (1 US gal = 3.785411784 L) - Area Square Metres To Square Feet
ft² = m² ÷ 0.09290304 (1 ft = 0.3048 m exactly) - Area Hectares To Acres
acre = ha × 10000 ÷ 4046.8564224 - Speed Kmh To Mph
mph = km/h × 1000 ÷ 1609.344 ; kn = km/h ÷ 1.852 - Pressure Bar To Psi
psi = Pa ÷ 6894.757293168361 (1 bar = 100000 Pa) - Energy Joules To Calories
cal = J ÷ 4.184 ; kWh = J ÷ 3600000 - Power Watts To Horsepower
hp = W ÷ 745.6998715822702 (550 ft·lbf/s) - Force Newtons To Pounds Force
lbf = N ÷ 4.4482216152605 (lbf = 0.45359237 kg × 9.80665 m/s²)
Gaming and probability
15 of 40 calculators shown- Dice Roll Probability
P(X ≥ t) = (s − t + 1) ÷ s ; P(at least once) = 1 − (1 − p)^n - At Least One Success
P(≥1) = 1 − (1 − p)^n - Drop Rate Attempts
E[n] = 1 ÷ p ; n(c) = ln(1 − c) ÷ ln(1 − p) - Gacha Pity Pulls
E = Σ k·p·(1 − p)^(k−1) + N·(1 − p)^N - Loot Probability
P(≥1 drop) = 1 − (1 − r)^n ; E[drops] = r × n - Xp To Next Level
XP(L) = base × L^k ; ΔXP = XP(L+1) − XP(L) - Levels From Xp
L = (XP ÷ base)^(1 ÷ k) - Damage Per Second
DPS = damage × [1 + c × (m − 1)] ÷ interval - Effective Health
EHP = HP ÷ (1 − DR) - Critical Hit Damage
D̄ = D × [1 + c × (m − 1)] - Hit Chance Accuracy Evasion
P(hit) = accuracy ÷ (accuracy + evasion) - Time To Farm Item
hours = (1 ÷ p) ÷ runs per hour - Grind Hours To Target
hours = XP needed ÷ XP per hour - Game Currency To Money
cost = amount × (bundle price ÷ bundle currency) - Fps To Frame Time
frame time (ms) = 1000 ÷ FPS
Astronomy and space
15 of 40 calculators shown- Weight On Planet
w_body = m × g_body ; w_body/w_Earth = g_body / g_Earth - Escape Velocity
v_esc = √(2 G M / R) - Orbital Velocity
v = √(G M / r) - Orbital Period
T = 2π √(a³ / (G M)) - Gravitational Force
F = G × m₁ × m₂ / r² - Light Travel Time
t = d / c - Light Years To Km
d = ly × 9 460 730 472 580 800 m - Parsecs To Light Years
d_ly = d_pc × (1 pc / 1 ly) = d_pc × 3.261563… - Astronomical Units To Km
d = AU × 149 597 870 700 m - Distance Modulus
m − M = 5 log₁₀(d / 10 pc) - Stellar Luminosity
L = 4π R² σ T⁴ - Wien Peak Wavelength
λ_max = b / T, b = 2.897771955 × 10⁻³ m·K - Schwarzschild Radius
r_s = 2 G M / c² - Telescope Magnification
M = f_telescope / f_eyepiece - Telescope Resolving Power
R = 116 / D(mm) (Dawes limit, arcseconds)
Music and audio
15 of 40 calculators shown- Note Frequency
f = f₀ × 2^(n ÷ 12) - Semitones Between Frequencies
n = 12 × log₂(f₂ ÷ f₁) - Cents Between Frequencies
cents = 1200 × log₂(f₂ ÷ f₁) - Bpm To Milliseconds
ms per beat = 60000 ÷ BPM - Note Delay Time
delay ms = (60000 ÷ BPM) × (4 ÷ note division) - Song Length In Bars
bars = length ÷ (beats per bar × 60 ÷ BPM) - Bars To Seconds
seconds = bars × beats per bar × 60 ÷ BPM - Sample Count
samples = duration × sample rate - Audio Bitrate File Size
bytes = bitrate ÷ 8 × duration - Wav File Size
bytes = sample rate × bit depth ÷ 8 × channels × seconds - Decibel Gain Ratio
amplitude ratio = 10^(dB ÷ 20) - Decibel Sum
L = 10 × log₁₀(10^(L₁÷10) + 10^(L₂÷10)) - Sound Distance Attenuation
L₂ = L₁ − 20 × log₁₀(d₂ ÷ d₁) - Sound Wavelength
λ = 343 ÷ f (air at 20 °C) - Room Mode Frequency
f = 343 ÷ (2 × L)
Insurance and risk
15 of 40 calculators shown- Life Insurance Need
Need = (income × years + final expenses) − (assets + existing coverage) - Term Life Premium
Premium = (face ÷ 1000) × rate per thousand + policy fee - Disability Income Benefit
Benefit = min(income × benefit %, cap); total = benefit × months - Out Of Pocket Total
Member = min(deductible + coinsurance % × (claims − deductible), OOP max) - Deductible Premium Breakeven
Breakeven claims = low deductible + (low premium − high premium) - Coinsurance Share
Member coinsurance = covered charges × coinsurance % - Copay Annual Total
Total copays = visits × copay per visit + other copays - Hsa Contribution Growth
FV = B0 × (1+r)^n + C × [((1+r)^n − 1) ÷ r] × (1+r) - Deductible Savings
Savings = premium(low deductible) − premium(high deductible); payback = Δdeductible ÷ savings - Claim Payout After Deductible
Payout = min(max(loss − deductible, 0), policy limit) - Replacement Cost Vs Acv
ACV = RC − (RC − salvage) × min(age ÷ useful life, 1) - Rebuild Cost Coverage
Rebuild = cost/ft² × area; required = rebuild × coinsurance % - Contents Coverage Percentage
Contents limit = dwelling limit × contents % - Umbrella Liability Gap
Total protection = primary limit + umbrella limit; gap = exposure − total - Business Interruption Loss
BI loss = (revenue × gross margin % + continuing expenses) × months
Farming and crops
15 of 40 calculators shown- Crop Yield Per Hectare
Yield = harvested mass ÷ area - Total Harvest Tonnage
Harvest = yield per hectare × area - Seeding Rate Per Hectare
Seeding rate (kg/ha) = plants/m² × TSW(g) ÷ 100 ÷ (germination × establishment) - Seed Quantity For Area
Seed required = seeding rate × area - Plant Population Spacing
Plants per hectare = 10 000 m² ÷ (row spacing × plant spacing) - Fertiliser Rate Per Hectare
Fertiliser rate = nutrient requirement ÷ (grade % ÷ 100) - Nitrogen From Fertiliser Grade
N supplied = fertiliser rate × (N % ÷ 100) - Lime Requirement
Lime (t/ha) = (target pH − soil pH) × buffer factor ÷ (neutralising value ÷ 100) - Manure Spread Rate
Nutrient = manure rate × nutrient per tonne × availability - Irrigation Water Volume
Volume (m³) = area (ha) × depth (mm) × 10 ÷ efficiency - Irrigation Run Time
Run time = water volume ÷ flow rate - Evapotranspiration Water Need
ETc = Kc × ETo; irrigation need = ETc − effective rainfall - Pesticide Tank Mix
Product per tank = (tank volume ÷ spray volume per ha) × product rate - Spray Coverage Per Hectare
L/ha = total nozzle output (L/min) × 600 ÷ (speed km/h × boom width m) - Field Bale Yield
Bales = yield × area × (1 − losses) × 1000 ÷ bale weight
Crafts and sewing
15 of 40 calculators shown- Fabric Yardage Garment
L = ceil(n ÷ floor(W ÷ w)) × l × (1 + ease) - Fabric From Pattern Pieces
L = (w × l × n × (1 + waste)) ÷ W - Seam Allowance Total
A = 2 × sa × Ls × n - Quilt Binding Length
B = 2 × (W + L) + 25 ; strips = ceil(B ÷ fabric width) - Quilt Backing Fabric
panels = ceil((W + 2o) ÷ fabric width) ; L = panels × (Lq + 2o) - Quilt Block Count
blocks = ceil(W ÷ s) × ceil(L ÷ s) - Knitting Stitch Count
sts = width × (gauge ÷ 10) - Knitting Row Count
rows = length × (gauge ÷ 10) - Yarn Quantity Project
m = (w × l ÷ 10000) × density × (1 + allowance) - Yarn Skeins Needed
skeins = ceil(yarn needed ÷ skein weight) - Crochet Chain Length
ch = round(width × (gauge ÷ 10)) + turning chains - Cross Stitch Fabric Size
size = stitches ÷ (count ÷ 2.54) + 2 × margin - Bead Count Length
beads = length ÷ bead diameter - Jewellery Wire Length
L = per-link × links × (1 + waste) - Candle Wax Quantity
m = V × fill × n × ρ
Sport statistics
15 of 40 calculators shown- Batting Average
AVG = H ÷ AB - On Base Percentage
OBP = (H + BB + HBP) ÷ (AB + BB + HBP + SF) - Slugging Percentage
SLG = (1B + 2×2B + 3×3B + 4×HR) ÷ AB - Earned Run Average
ERA = 9 × ER ÷ IP - Whip Baseball
WHIP = (BB + H) ÷ IP - Field Goal Percentage
FG% = FGM ÷ FGA × 100 - True Shooting Percentage
TS% = PTS ÷ (2 × (FGA + 0.44 × FTA)) × 100 - Points Per Game
PPG = total points ÷ games played - Player Efficiency Rating
EFF = (PTS + REB + AST + STL + BLK − (FGA − FGM) − (FTA − FTM) − TO) ÷ G - Passer Rating
Rating = ((a + b + c + d) ÷ 6) × 100, each component clamped to 0–2.375 - Yards Per Attempt
Y/A = yards ÷ attempts; AY/A = (yards + 20×TD − 45×INT) ÷ attempts - Completion Percentage
Cmp% = completions ÷ attempts × 100 - Goals Per 90
G/90 = goals ÷ minutes played × 90 - Win Probability Points
xPts = (3 × P(win) + 1 × P(draw)) × matches - Service Percentage
1st serve % = first serves in ÷ service points played × 100
Weather and climate
15 of 40 calculators shown- Wind Chill
Twc = 13.12 + 0.6215×T − 11.37×v^0.16 + 0.3965×T×v^0.16 (T in °C, v in km/h) - Heat Index
HI = Rothfusz regression on (T °F, RH %), with the NWS dry and humid adjustments - Dew Point
Td = b×γ ÷ (a − γ), γ = a×T÷(b+T) + ln(RH÷100), a = 17.27, b = 237.7 °C - Relative Humidity From Dew Point
RH = 100 × e(Td) ÷ es(T), with e(T) = 6.112×exp(17.27×T ÷ (237.7+T)) hPa - Absolute Humidity
AH = e ÷ (Rv × T), Rv = 461.5 J/(kg·K), e = es(T) × RH÷100 - Wet Bulb Temperature
Tw = T×atan(0.151977×√(RH+8.313659)) + atan(T+RH) − atan(RH−1.676331) + 0.00391838×RH^1.5×atan(0.023101×RH) − 4.686035 - Apparent Temperature
AT = T + 0.33×e − 0.70×v − 4.00, e = RH÷100 × 6.105×exp(17.27×T ÷ (237.7+T)) - Cloud Base Height
Cloud base (m) = (T − Td) × 125 (Espy's rule, dry adiabatic 9.8 °C/km vs dew point 1.8 °C/km) - Pressure Altitude
PA = field elevation + (1013.25 − QNH) × 8.2296 m/hPa (27 ft per hPa, ISA) - Density Altitude
ρ = p ÷ (Rd×T); DA = (T0÷L) × [1 − (ρ÷ρ0)^(1÷(g÷(Rd×L) − 1))], ISA T0 = 288.15 K, L = 0.0065 K/m - Rainfall Volume
V (L) = rainfall (mm) × area (m²) [1 mm over 1 m² = 1 L] - Rainfall Intensity
I = rainfall depth ÷ duration; WMO bands 1 light (<2.5), 2 moderate, 3 heavy, 4 violent (mm/h) - Snow Water Equivalent
SWE (mm) = depth (mm) × ρ_snow ÷ ρ_water, ρ_water = 1000 kg/m³ - Snow Roof Load
load (kg/m²) = depth (m) × ρ_snow; pressure (kPa) = load × g ÷ 1000, g = 9.80665 m/s² - Cooling Degree Days
CDD = Σ max(0, T_mean − T_base) over the period (mean-temperature method)
Investing and markets
15 of 40 calculators shown- Cagr Calculator
CAGR = (ending ÷ beginning)^(1 ÷ years) − 1 - Rule Of 72
Years to double ≈ 72 ÷ annual rate (%) - Price To Earnings Ratio
P/E = share price ÷ earnings per share - Earnings Per Share
EPS = (net income − preferred dividends) ÷ shares outstanding - Price To Book Ratio
P/B = share price ÷ book value per share - Dividend Yield
Dividend yield = annual dividend per share ÷ share price - Dividend Payout Ratio
Payout ratio = dividend per share ÷ earnings per share - Book Value Per Share
BVPS = (total equity − preferred equity) ÷ shares outstanding - Market Capitalisation
Market cap = share price × shares outstanding - Enterprise Value
EV = market cap + total debt − cash and equivalents - Free Cash Flow Yield
FCF yield = free cash flow ÷ market capitalisation - Present Value Future Sum
PV = FV ÷ (1 + r)^n - Future Value Lump Sum
FV = PV × (1 + r)^n - Net Present Value Annuity
NPV = C × [1 − (1 + r)^−n] ÷ r − initial investment - Irr Approximation
IRR solves: C × [1 − (1 + IRR)^−n] ÷ IRR = initial investment
Electrical engineering
15 of 40 calculators shown- Resistors Series
R_total = R1 + R2 + R3 - Resistors Parallel
1/R_total = 1/R1 + 1/R2 + 1/R3 - Capacitors Series
1/C_total = 1/C1 + 1/C2 + 1/C3 - Capacitors Parallel
C_total = C1 + C2 + C3 - Voltage Divider
Vout = Vin × R2 / (R1 + R2) - Current Divider
I1 = I × R2 / (R1 + R2) - Led Series Resistor
R = (Vsupply − Vforward) / Iled - Rc Time Constant
τ = R × C - Rl Time Constant
τ = L / R - Lc Resonant Frequency
f = 1 / (2π × √(L × C)) - Capacitive Reactance
Xc = 1 / (2π × f × C) - Inductive Reactance
XL = 2π × f × L - Series Rlc Impedance
Z = √(R² + (XL − Xc)²) - Power Factor Correction
Qc = P × (tan(arccos φ1) − tan(arccos φ2)) - Three Phase Power
P = √3 × VL × IL × cos φ
Nutrition and diet
15 of 40 calculators shown- Calories From Macros
kcal = (protein g × 4) + (carbohydrate g × 4) + (fat g × 9) - Macro Split From Calories
grams = (kcal × share% ÷ 100) ÷ Atwater factor (4, 4 or 9 kcal/g) - Protein Per Kilogram
protein g = body weight kg × g per kg (protein = 4 kcal/g) - Calorie Deficit Rate
daily deficit = (kg per week × 7700 kcal/kg) ÷ 7 - Weight Change From Surplus
kg gained = (daily surplus kcal × days) ÷ 7700 kcal/kg - Net Carbs
net carbs = total carbohydrate − fibre − sugar alcohols (carbohydrate = 4 kcal/g) - Fibre Target
fibre g = daily kcal × 14 g per 1000 kcal - Sugar Percent Calories
% of calories = (sugar g × 4 kcal/g) ÷ daily kcal × 100 - Alcohol Calories
kcal = volume mL × ABV% ÷ 100 × 0.789 g/mL × 7 kcal/g - Water Intake Weight
mL = body weight kg × 35 mL/kg + exercise minutes × 12 mL/min - Caffeine Limit
upper intake = body weight kg × 6 mg/kg (moderate = 3 mg/kg) - Sodium From Salt
sodium g = salt g × 0.393 - Calories Per Step
kcal = 0.9 kcal/kg/km × body weight kg × (steps × stride cm ÷ 100 000) - Energy Density
kcal per 100 g = (energy kcal ÷ mass g) × 100 (1 kcal = 4.184 kJ) - Portion Calories
portion kcal = kcal per 100 g × portion g ÷ 100
Logistics and shipping
15 of 40 calculators shown- Volumetric Weight
Volumetric weight = (L × W × H) ÷ dimensional divisor - Chargeable Weight
Chargeable weight = max(actual weight, volumetric weight) - Pallets Per Container
Pallets = max(⌊L÷l⌋ × ⌊W÷w⌋, ⌊L÷w⌋ × ⌊W÷l⌋) - Cartons Per Pallet
Cartons = cartons per layer × ⌊usable height ÷ carton height⌋ - Container Fill Percentage
Fill % = cargo volume ÷ container internal volume × 100 - Shipment Volume Cbm
CBM = (L × W × H in cm ÷ 1 000 000) × pieces - Freight Cost Per Kg
Cost per kg = total freight cost ÷ chargeable weight - Freight Cost Per Cbm
Cost per CBM = total freight cost ÷ shipment volume - Cost Per Unit Shipped
Cost per unit = (freight + fees) ÷ units shipped - Fuel Surcharge
Fuel surcharge = base freight × rate ÷ 100 - Customs Duty
Duty = customs value × duty rate ÷ 100 - Landed Cost
Landed cost = goods + freight + insurance + duty + other fees - Warehouse Storage Cost
Monthly cost = pallets × rate per pallet per week × weeks per month - Pick Rate Per Hour
Pick rate = lines picked ÷ hours worked - Order Cycle Time
Cycle time = processing + transit + final delivery
Design and printing
15 of 40 calculators shown- Pixels To Print Size
inches = pixels ÷ DPI - Print Size To Pixels
pixels = inches × DPI - Dpi From Pixels
DPI = pixels ÷ inches - Image Aspect Ratio
ratio = width ÷ height, reduced by GCD(width, height) - Resize To Aspect Ratio
new height = new width × (original height ÷ original width) - Megapixels From Dimensions
MP = (width × height) ÷ 1 000 000 - Bleed And Trim Size
bleed size = trim size + 2 × bleed per edge - Sheets From Page Count
sheets = ceil(pages ÷ pages per sheet) - Gsm To Paper Pounds
lb = gsm × basis sheet area (m²) × 500 ÷ 453.59237 - Ream Weight
sheet mass (g) = gsm × area (m²); ream = sheet mass × sheet count - Ink Coverage Percentage
TAC = C% + M% + Y% + K% - Signature Page Rounding
rounded pages = ceil(pages ÷ pages per signature) × pages per signature - Book Spine Width
spine = (pages ÷ PPI) + cover thickness - Scale Factor Between Sizes
scale = output size ÷ source size - Golden Ratio Dimension
φ = (1 + √5) ÷ 2; longer = side × φ, shorter = side ÷ φ
Pool and aquarium
15 of 40 calculators shown- Pool Volume Rectangular
V = L × W × (shallow + deep) ÷ 2 - Pool Volume Round
V = π × (d ÷ 2)² × depth - Pool Volume Oval
V = π × (a ÷ 2) × (b ÷ 2) × depth - Pool Volume Kidney
V ≈ 0.45 × (A + B) × L × depth - Aquarium Tank Volume
V = L × W × H − (L × W × substrate depth) - Pool Chlorine Dose
product = (target − current) × volume(m³) ÷ (strength ÷ 100) - Pool Shock Dose
shock = raise(ppm) × volume(m³) ÷ (strength ÷ 100) - Pool Ph Adjuster Dose
product = |ΔpH| ÷ 0.1 × label dose × volume(m³) - Pool Alkalinity Increase
product = (target − current) × label dose × volume(m³) - Pool Calcium Hardness Increase
product = (target − current) × label dose × volume(m³) - Pool Cyanuric Acid Dose
product = (target − current) × volume(m³) ÷ (strength ÷ 100) - Pool Salt Addition
salt = (target − current) × volume(m³) ÷ (purity ÷ 100) - Pool Turnover Time
turnover time = volume ÷ flow rate - Pool Filter Run Time
run time = (volume ÷ flow rate) × turnovers per day - Pool Heating Energy
Q = m × c × ΔT, c = 4186 J/kg·K
Aviation and marine
15 of 40 calculators shown- True Airspeed
TAS = IAS ÷ √(ρ ÷ ρ₀) - Ground Speed Wind
GS = TAS − V × cos(wind − course) - Crosswind Component
Crosswind = V × sin(θ) - Headwind Component
Headwind = V × cos(θ) - Rate Of Climb Required
ROC = altitude gain ÷ (distance ÷ GS × 60) - Glide Path Descent Rate
ROD = GS × tan(γ) × 6076.11548556556 ÷ 60 - Top Of Descent Distance
TOD distance = GS × (altitude ÷ ROD) ÷ 60 - Leg Fuel Burn
Fuel = (distance ÷ GS) × fuel flow - Fuel Reserve Endurance
Usable endurance = (fuel on board − reserve) ÷ fuel flow - Weight And Balance Moment
Moment = weight × arm - Centre Of Gravity Position
CG = Σ(weight × arm) ÷ Σ weight - Takeoff Distance Density Altitude
DA = PA + 118.8 × (OAT − ISA temp); distance = SL × (1 + k)^(DA ÷ 1000) - Glide Ratio
Glide ratio = horizontal distance ÷ height lost - Wind Correction Angle
WCA = asin(V × sin(wind − course) ÷ TAS) - Nautical Miles To Kilometres
1 NM = 1852 m exactly
Property management
15 of 40 calculators shown- Rent Affordability
Affordable rent = gross monthly income × rent-to-income limit ÷ 100 - Rent Increase Percentage
Increase % = (new rent − old rent) ÷ old rent × 100 - Rent Proration
Prorated rent = monthly rent ÷ days in month × days occupied - Security Deposit Interest
Interest = deposit × annual rate ÷ 100 × years held - Tenant Turnover Cost
Turnover cost = lost rent + make-ready + marketing + leasing commission - Vacancy Rate
Vacancy rate = vacant units ÷ total units × 100 - Occupancy Rate
Occupancy rate = occupied units ÷ total units × 100 - Effective Gross Income
EGI = gross potential rent − vacancy and credit loss + other income - Operating Expense Ratio
OER = operating expenses ÷ effective gross income × 100 - Net Operating Income
NOI = (gross potential rent − vacancy loss + other income) − operating expenses - Debt Service Coverage Ratio
DSCR = net operating income ÷ annual debt service - Cash On Cash Return
Cash on cash = annual cash flow ÷ cash invested × 100 - Break Even Occupancy
Break-even occupancy = (operating expenses + debt service) ÷ gross potential rent × 100 - Property Management Fee
Management fee = collected rent × fee % ÷ 100 - Maintenance Reserve Per Unit
Maintenance reserve = gross potential rent × reserve % ÷ 100
Woodworking and metalwork
15 of 40 calculators shown- Board Feet
bf = T(in) × W(in) × L(in) ÷ 144 - Board Foot Lumber Cost
Cost = bf × (1 + waste ÷ 100) × price per bf - Linear Metres From Area
L = area ÷ board width, then × (1 + waste ÷ 100) - Sheet Goods Yield
n = floor((panel + kerf) ÷ (part + kerf)) in each direction - Kerf Waste
Kerf loss = kerf × number of cuts - Wood Moisture Shrinkage
S% = total shrinkage × (MCi − MCf) ÷ fibre saturation point - Wood Movement Across Grain
ΔW = W × CT × ΔMC - Shelf Sag Deflection
δ = 5 × w × L⁴ ÷ (384 × E × I), I = b × h³ ÷ 12 - Mitre Angle Polygon
Mitre = 180 ÷ n, saw setting = 90 − 180 ÷ n - Compound Mitre Angle
tan(mitre) = cos(slope) × tan(180 ÷ n); sin(bevel) = sin(slope) × cos(180 ÷ n) - Dowel Spacing
Spacing = (length − 2 × margin) ÷ (dowels − 1) - Screw Pilot Hole
Pilot Ø = screw Ø × ratio ÷ 100 - Glue Clamping Pressure
P = (clamps × force per clamp) ÷ glue area - Wood Weight Volume
m = V × ρ × (1 + MC ÷ 100) - Metal Bar Weight
m = L × W × T × ρ
Academic and research
15 of 40 calculators shown- Assignment Weighted Score
Grade = Σ(score × weight) ÷ Σ(weight) - Final Exam Score Needed
Needed = (target − current × (1 − w)) ÷ w - GPA From Credit Points
GPA = quality points ÷ credits - Cumulative GPA Update
Cumulative GPA = Σ(GPA × credits) ÷ Σ(credits) - Letter Grade Threshold Gap
Gap = threshold% − current%; points = gap ÷ 100 × total points - Class Rank Percentile
Percentile = (N − rank) ÷ N × 100 - Exam Curve Adjustment
Curved = raw × (100 ÷ class maximum) - Pass Mark Shortfall
Shortfall = pass mark% − score% - Study Hours Per Credit
Hours per credit = weekly study hours ÷ credits - Reading Time From Words
Minutes = words ÷ words per minute - Reading Words Per Minute
WPM = words read ÷ minutes - Net Typing Wpm
Net WPM = (characters ÷ 5 − errors) ÷ minutes - Essay Section Words
Body per section = (total − intro − conclusion) ÷ sections - H Index Threshold
Next h needs (h + 1) papers each cited (h + 1) times - Sample Size For Mean
n = (z × σ ÷ E)²
Beauty and personal care
15 of 40 calculators shown- Hair Dye Developer Ratio
developer = colour × ratio - Hair Colour Amount By Length
colour = (length ÷ 10) × g per 10 cm × thickness factor - Bleach Mixing Ratio
developer = powder × ratio - Skincare Product Duration
days = volume ÷ (dose × applications per day) - Moisturiser Per Application
dose = area × rate (mg/cm²) - Sunscreen Body Amount
BSA = 0.007184 × height^0.725 × weight^0.425; dose = area × 2 mg/cm² - Sunscreen Reapplication Interval
protection time = SPF × unprotected burn time (a simplification) - Perfume Dilution Concentration
C1 × V1 = C2 × V2 - Essential Oil Dilution Drops
drops = carrier mL × dilution% × drops per mL - Lotion Preservative Percentage
preservative = batch mass × percentage - Shampoo Cost Per Wash
cost per wash = price ÷ (bottle mL ÷ dose mL) - Salon Cost Per Year
annual cost = (52 ÷ weeks between visits) × price × (1 + tip%) - Hair Growth Target Length
months = (target − current) ÷ (monthly growth − monthly trim) - Nail Growth Time
months = (target − current) ÷ monthly growth - Shaving Blade Cost Per Year
annual cost = (shaves per year ÷ shaves per blade) × blade price
Retirement planning
15 of 40 calculators shown- Safe Withdrawal Amount
W = P × r - Portfolio Longevity
n = -ln(1 - P × r ÷ W) ÷ ln(1 + r) - Required Nest Egg
P = S ÷ r - Monthly Savings For Target
PMT = FV × i ÷ ((1 + i)^n - 1) - Years To Financial Independence
n = ln((T + S ÷ r) ÷ (C + S ÷ r)) ÷ ln(1 + r) - Fire Number
FIRE = (monthly expenses × 12) ÷ r - Coast Fire Number
Coast = F ÷ (1 + r)^n - Annuity Income From Lump Sum
PMT = L × i ÷ (1 - (1 + i)^-n) - Lump Sum For Annuity Income
L = PMT × (1 - (1 + i)^-n) ÷ i - Pension Lump Sum Value
PV = A × (1 - (1 + d)^-n) ÷ d - Benefit From Replacement Rate
B = E × rate - Income Replacement Ratio
Ratio = retirement income ÷ pre-retirement income - Inflation Adjusted Spending
S_n = S × (1 + i)^n - Real Return After Inflation
r_real = (1 + r_nominal) ÷ (1 + i) - 1 - Sequence Risk First Year Drawdown
End = P × (1 + r) - W
Legal and admin
15 of 40 calculators shown- Billable Hours Invoice
Total = hours × rate × (1 − discount%) + expenses - Contingency Fee Share
Fee = fee base × contingency% ; client net = recovery − costs − fee - Settlement Net Proceeds
Net = settlement − fee − costs − liens - Court Filing Cost Total
Total = filing + (service × parties) + (pages × per page) + other - Damages Prejudgment Interest
Interest = principal × annual rate × days ÷ day-count basis - Statutory Interest Accrual
A = P × (1 + r ÷ n)^(n × t) - Late Payment Penalty
Penalty = fixed + invoice × rate% × periods late - Child Support Income Share
Share = payer income ÷ combined income ; obligation = total × share × (1 − parenting time%) - Spousal Support Duration
Duration = marriage years × factor (low and high bounds you supply) - Asset Split Percentage
Divisible = assets − debts − excluded ; share = divisible × share% - Estate Distribution Per Heir
Share = (estate − debts − bequests) ÷ number of heirs - Probate Fee Estimate
Fee = max(base + (estate − threshold) × rate%, minimum) - Inheritance Share With Spouse
Spouse = estate × fraction ; each child = (estate − spouse share) ÷ children - Notice Period Pay
Weeks = min(base + per-year × years, cap) ; pay = weeks × weekly pay - Severance Weeks Per Year
Severance = min(years × weeks per year, cap) × min(weekly pay, pay cap)
Endurance training
15 of 20 calculators shown- Marathon From Half
T_marathon = T_half × (42.195 ÷ 21.0975)^1.06 - Pace Band Splits
t_split = (T ÷ D) × d_split - Negative Split Pace
t1 = T ÷ (2 − p), t2 = t1 × (1 − p) - Treadmill Incline Pace
VO2 = 0.2×S + 0.9×S×grade + 3.5 (S in m/min) - Heart Rate Drift
Drift % = (HR2 − HR1) ÷ HR1 × 100 - Lactate Threshold Pace
Threshold pace = t ÷ (d ÷ 1000) - Threshold Training Zones
Zone pace = threshold pace ÷ (zone %speed ÷ 100) - Weekly Mileage Progression
V_n = V_0 × (1 + p)^n - Acute Chronic Workload
ACWR = acute 7-day load ÷ (chronic 28-day load ÷ 4) - Trimp Training Impulse
TRIMP = t × ΔHR × 0.64 × e^(1.92 × ΔHR) - Running Economy
RE = VO2 ÷ speed (ml O2 per kg per km) - Energy Cost Of Running
E = Cr × m × d - Carb Intake Per Hour
Carb total = rate (g/h) × duration (h) - Sodium Replacement
Na = sweat rate × [Na] × duration - Race Fuelling Plan
Totals = hourly rate × race duration
HVAC and plumbing
15 of 20 calculators shown- Air Conditioner Sizing
BTU/h = (area_ft² × 20 + 600 × extra occupants) × (1 + sun %) - Heating Load Volume
Q = V × f × (Tin − Tout) - Btu To Kilowatts
kW = BTU/h ÷ 3412.142 - Kilowatts To Btu
BTU/h = kW × 3412.142 - Duct Airflow Cfm
Q = V × ACH - Duct Velocity
v = Q ÷ A - Duct Size From Flow
A = Q ÷ v, D = √(4A ÷ π) - Air Changes Per Hour
ACH = CFM × 60 ÷ volume_ft³ - Fan Power
P = Q × Δp ÷ η - Radiator Output Sizing
Q50 = V × f × ΔTroom ÷ (ΔTrad ÷ 50)^1.3 - Underfloor Heating Pipe Length
L = A ÷ spacing + 2 × manifold run - Boiler Size From Radiators
Boiler = Σ radiator output × (1 + margin) - Pipe Water Volume
V = π × (D ÷ 2)² × L - Pipe Flow Rate
Q = v × π × (D ÷ 2)² - Pipe Pressure Drop Hazen Williams
hf = 10.67 × L × Q^1.852 ÷ (C^1.852 × D^4.87)
Creator economy
15 of 20 calculators shown- Engagement Rate
Engagement rate = (likes + comments + shares + saves) ÷ followers × 100 - Engagement Rate By Reach
Engagement rate = interactions ÷ reach × 100 - Follower Growth Rate
Growth rate = (end − start) ÷ start × 100 - Video Ad Revenue
Revenue = monetized views ÷ 1000 × CPM - Revenue Share After Cut
Creator revenue = gross × (1 − platform cut ÷ 100) - Subscription Revenue
Revenue = subscribers × price, net = gross × (1 − cut ÷ 100) - Churn Adjusted Subscribers
Sn = S0 × (1 − churn)^n + new × Σ(1 − churn)^i - Sponsorship Rate
Fee = followers ÷ 1000 × rate per 1000 - Affiliate Commission
Commission = sale amount × rate ÷ 100 × sales - Affiliate Earnings Per Click
EPC = conversion rate ÷ 100 × commission per sale - Newsletter Open Rate
Open rate = opens ÷ delivered × 100 - Click To Open Rate
CTOR = clicks ÷ opens × 100 - Unsubscribe Rate
Unsubscribe rate = unsubscribes ÷ delivered × 100 - Podcast Download Revenue
Revenue = downloads ÷ 1000 × CPM × ad slots × fill rate - Streaming Royalty Payout
Payout = plays × rate per play × artist share ÷ 100
Advanced geometry
15 of 20 calculators shown- Pyramid Volume
V = (1/3) × a² × h, A = a² + 2 × a × √(h² + (a/2)²) - Frustum Volume
V = (h/3) × (A₁ + A₂ + √(A₁ × A₂)) - Torus Volume
V = 2 × π² × R × r², A = 4 × π² × R × r - Tetrahedron Volume
V = a³ ÷ (6√2) - Octahedron Volume
V = (√2 ÷ 3) × a³ - Prism Volume
V = A_base × h - Hexagonal Prism Volume
V = (3√3 ÷ 2) × a² × h - Spherical Cap Volume
V = (π × h² ÷ 3) × (3R − h) - Spherical Sector Volume
V = (2/3) × π × R² × h - Cylinder Surface Area
A = 2πr² + 2πrh - Cone Slant Height
l = √(r² + h²), A_lat = π × r × l - Parallelogram Area
A = a × b × sin(θ) - Rhombus Area
A = (d₁ × d₂) ÷ 2 - Kite Area
A = (d₁ × d₂) ÷ 2 - Cyclic Quadrilateral Area
A = √((s−a)(s−b)(s−c)(s−d)), s = (a+b+c+d)/2
Household and budget
15 of 20 calculators shown- Appliance Cost Per Use
cost per use = (purchase price − resale value) ÷ uses + running cost per use - Laundry Cost Per Load
cost per load = detergent + electricity + water - Grocery Cost Per Person
per person per week = total spend ÷ (people × weeks) - Household Bill Split
share = total bill ÷ housemates - Utility Split By Rooms
my share = total bill × (my rooms ÷ total rooms) - Subscription Yearly Total
annual = monthly price × subscriptions × 12 + yearly fees - Subscription Cost Per Use
cost per use = monthly price ÷ uses per month - Bulk Unit Price Comparison
unit price = pack price ÷ pack quantity - Discount Final Price
final price = list price × (1 − discount ÷ 100) - Successive Discounts
final price = list price × (1 − d₁ ÷ 100) × (1 − d₂ ÷ 100) - Price Per 100g Comparison
price per 100 g = price ÷ weight (g) × 100 - Coupon Break Even Quantity
break-even quantity = fee ÷ saving per item - Petrol Vs Transit Monthly
car cost = distance × days × (L/100 km ÷ 100) × fuel price + parking × days - Daily Habit Yearly Cost
annual cost = cost each time × times per week × 52 - Moving Cost Estimate
total = fixed fee + volume × price per m³ + distance × price per km
Loans and debt
12 of 12 calculators shown- Loan Amortization Schedule
M = P[r(1+r)^n]/[(1+r)^n−1] - Extra Payment Savings
saving = interest(base) − interest(base + extra) - Lump Sum Payment Impact
balance′ = balance − lump sum, payment unchanged - Refinance Break Even
break-even = cost ÷ (old payment − new payment) - Biweekly Payment Plan
biweekly = monthly ÷ 2, paid every 14 days (26/year) - Credit Card Minimum Trap
payment = max(balance × %, floor), recomputed monthly - Car Loan Schedule
financed = price − down payment − trade-in - Loan Affordability By Income
P = M × [1 − (1+r)^−n] ÷ r - Student Loan Grace Cost
B′ = B × (1 + r)^grace months - Debt Avalanche Two Loans
highest rate first; minimum elsewhere (avalanche) - Interest Only Then Amortizing
IO: M = P × r; then M = P[r(1+r)^n]/[(1+r)^n−1] - Balloon Payment Loan
M amortizes P − balloon/(1+r)^n over n periods
Portfolio growth
12 of 12 calculators shown- Compound Growth With Contributions
FV = P(1+i)^n + PMT[((1+i)^n − 1)/i] - Lump Sum Growth Over Time
FV = P(1 + r/m)^(m·t) - Dca Vs Lump Sum
FV(DCA) = Σ (T/k)(1+i)^(n−j) vs FV(lump) = T(1+i)^n - Rebalancing Drift Projection
rebalanced: V·[w(1+rs) + (1−w)(1+rb)] each year; drift: V·w(1+rs)^t + V(1−w)(1+rb)^t - Fee Drag Over Time
net rate = gross − fee; cost = FV(gross) − FV(gross − fee) - Inflation Adjusted Portfolio
real FV = nominal FV / (1 + π)^t; real rate = (1+r)/(1+π) − 1 - Dividend Reinvestment Growth
V(t) = V(t−1)(1+g) + V(t−1)·y(t), y(t) = y₀(1+gd)^(t−1)/(1+g)^(t−1) - Savings Goal Timeline
n = ln[(PMT + i·FV)/(PMT + i·PV)] / ln(1+i) - Emergency Fund Buildup
target = monthly expenses × months of cover; balance grows by PMT + i·B each month - Education Fund Projection
cost = Σ C₀(1+c)^(k+s); fund = FV of PV plus monthly PMT - House Deposit Savings Plan
save until B(n) ≥ price·d·(1+p)^(n/12) - Million Milestone Timeline
B(n) = B(n−1)(1+i) + PMT·(1+g)^⌊n/12⌋, solved for B(n) ≥ M
Retirement drawdown
12 of 12 calculators shown- Drawdown Depletion Timeline
Bₜ = (Bₜ₋₁ − W) × (1 + r) - Withdrawal Rate Sustainability Path
W_max = B ÷ [(1 − (1+r)^−n) ÷ r] - Inflation Indexed Withdrawal Path
Wₜ = W₁ × (1 + i)^(t−1); Bₜ = (Bₜ₋₁ − Wₜ)(1 + r) - Sequence Of Returns Comparison
same returns, reordered: Bₜ = (Bₜ₋₁ − W)(1 + rₜ) - Bucket Strategy Drawdown Path
spend cash → bonds → equities; each bucket grows at its own r - Annuity Versus Drawdown Path
annuity income = B × share × payout; portfolio covers the rest - Phased Retirement Income Bridge
Wₜ = spending − wage while working, spending after - Minimum Distribution Drawdown Path
RMDₜ = Bₜ₋₁ ÷ divisorₜ, divisorₜ = d₀ − decline × (t − 1) - Pension Plus Portfolio Income Path
gapₜ = target(1+i)^(t−1) − pension(1+g)^(t−1) - Legacy Value At Target Age
B_n = B₀(1+r)^n − W × [((1+r)^n − 1) ÷ r] × (1+r) - Guardrail Dynamic Withdrawal Path
cut if W/B > rate×(1+band); raise if W/B < rate×(1−band) - Delayed Retirement Drawdown Impact
contribute for d years at r, then draw W for the rest
Energy payback
12 of 12 calculators shown- Solar Panel Payback
cumulative(n) = −(cost − incentive) + Σ (bill_do_nothing(n) − bill_with_pv(n)) - Home Battery Payback
saving(n) = capacity × cycles × (1−d)^(n−1) × (peak − offpeak/η) × (1+g)^(n−1) - Heat Pump Vs Gas Boiler
saving(n) = (Q/η_boiler × p_gas − Q/COP × p_elec) × (1+g)^(n−1) + Δservice - Insulation Upgrade Payback
saving(n) = Q × reduction × price × (1+g)^(n−1) - Led Relamping Payback
saving(n) = N × (W_old − W_led)/1000 × h × price × (1+g)^(n−1) + Δlamp replacement - Ev Vs Petrol Total Cost
saving(n) = L × p_fuel(1+g_f)^(n−1) − kWh × p_elec(1+g_e)^(n−1) + Δservice - Double Glazing Payback
Q = U·A·DD·24/1000 ÷ η; saving(n) = (Q_old − Q_new) × price × (1+g)^(n−1) - Smart Thermostat Payback
saving(n) = Q × s × price × (1+g)^(n−1) − running cost - Solar Water Heating Payback
saving(n) = (Q·f/η × price − pump kWh × p_elec) × (1+g)^(n−1) − maintenance - Efficient Appliance Replacement
saving(n) = (kWh_old − kWh_new) × price × (1+g)^(n−1) - Energy Tariff Switch Savings
saving(n) = kWh × (p_old(1+g)^(n−1) − p_new(n)) + Δstanding charge - Home Retrofit Bundle Payback
cumulative(n) = −(cost − grant) + Σ (Q × r × price × (1+g)^(k−1) − maintenance)
Property projections
12 of 12 calculators shown- Rent Vs Buy Cumulative Cost
net buy = (deposit + fees + Σ payments + Σ costs) − (value − balance); net rent = Σ rent_y - Home Equity Buildup Path
equity_y = P(1+g)^y − B_y, where B_y is the amortized balance after 12y payments - Property Value Appreciation Path
V_y = V_{y−1}(1+g) + improvements; real V_y = V_y/(1+i)^y - Rental Cash Flow Projection
cash_y = rent_y(1−v) − [rent_y(1−v)·f + expenses_y] − mortgage_y - Overpayment Equity Impact
equity gained = B_y(no overpayment) − B_y(with overpayment) - Buy To Let Ten Year Return
return = Σ cash_y + [V_n(1−s) − B_n] − (deposit + fees) - Property Portfolio Growth Path
net worth_y = V_0(1+g)^y − B_y, with B_y amortized at payment + reinvestment/12 - Capital Gains On Property Sale
tax = max(V_n(1−s) − base − exemption, 0)·rate; net = V_n(1−s) − tax - Holiday Let Seasonal Income
net_y = (7·w_p·r_p + 7·w_o·r_o)·occ·(1−f) − expenses_y - House Price To Income Path
ratio_y = P_0(1+p)^y / [I_0(1+i)^y] - Stamp Duty Cost Recovery
recovery year = min{y : Σ_{k≤y} saving·(1+s)^{k−1} ≥ price·d + fees} - Downsizing Net Proceeds Projection
freed = V(1−s) − B − P_new(1+b) − moving; capital_y = freed(1+r)^y
Business projections
12 of 12 calculators shown- Startup Cash Runway
cash_t = cash_(t−1) + R₀(1+g)^(t−1) − B₀(1+b)^(t−1) - Revenue Growth Projection
R_t = R₀(1+g)^(t−1); profit_t = R_t·m − F - Mrr Growth With Churn
MRR_t = MRR_(t−1)·(1 − c + e) + new - Cohort Retention Revenue
customers_t = N·r^(t−1); contribution_t = customers_t·ARPU·(1−s) - Product Break Even Timeline
cum_t = −D + Σ [u₀(1+g)^(i−1)·(p − v) − F] - Expansion Loan Payback
M = P·r(1+r)^n/((1+r)^n−1); net_t = Σ (profit_i − M) - Hiring Cost Ramp
net_t = H·rev·min(t/ramp,1) − H·(S/12)(1+o); cum₀ = −H·recruiting - Inventory Cash Cycle
CCC = DIO + DSO − DPO; WC = COGS/day·DIO + sales/day·DSO − COGS/day·DPO - Equipment Lease Vs Buy
PV = Σ CF_t/(1+r)^t, buying adds P at t=0 and credits salvage at t=n - Marketing Payback Curve
A_t = A_(t−1)·r + S/CAC; LTV = margin/(1 − r) - Profit Reinvestment Compounding
P_(y+1) = P_y·(1 + k·ROI), where k is the reinvested share - Seasonal Cash Flow Projection
R_m = R̄·[1 + s·cos(2π(m − peak)/12)]; cash_m = cash_(m−1) + R_m(1−v) − F
Health progress
12 of 12 calculators shown- Weight Loss Timeline
weekly Δkg = (daily deficit × 7) ÷ 7700; weeks = (start − target) ÷ weekly Δkg - Weight Gain Timeline
weekly Δkg = (daily surplus × 7) ÷ 7700; lean kg = Δkg × lean share - Body Fat Reduction Projection
lean = W₀(1−bf₀) held fixed; W(t) = lean + fat₀ − 7d·t/7700; bf% = fat ÷ W - Marathon Mileage Buildup
mileage(w) = min(start × (1+r)^(w−1), peak); taper halves the peak weekly - Strength Linear Progression
load(w) = load(w−1) + increment, ×(1−deload%) on every Nth week - Couch To 5k Progression
minutes(w) = min(start + gain × (w−1), target); weekly = minutes × sessions - Step Goal Ramp
steps(w) = min(start × (1+r)^(w−1), goal); w* = 1 + ln(goal/start) ÷ ln(1+r) - Habit Streak Compounding
index = (1 + g)^(days held); days held = (7 − missed) × weeks - Sleep Debt Recovery
debt(w) = max(debt(w−1) + 5(need − actual) − weekend recovery, 0) - Hydration Deficit Accumulation
cumulative L = (target − actual) × 7 × weeks; 1 L of water ≈ 1 kg - Muscle Gain Rate Projection
rate(t) = year-1 rate ÷ 2^(training age in years); lean(w) = lean(w−1) × (1 + rate/52) - Detraining Fitness Decay
V(t) = floor + (V₀ − floor) × 2^(−t/h), h′ = h ÷ (1 − maintained share)
Career and income
12 of 12 calculators shown- Salary Growth Projection
S(t) = S₀ × (1+g)^(t−1) × (1+p)^⌊(t−1)/k⌋, S_real = S(t) ÷ (1+i)^(t−1) - Job Offer Comparison
P(t) = S × (1+g)^(t−1) × (1+b), advantage = ΣP_B − ΣP_A - Career Break Cost
cost = Σ S_base(t) − Σ S_break(t), S_break = S_base × (1 − penalty × max(0, 1 − (τ−1)/r)) - Further Study ROI
NPV = Σ (C_study,t − C_base,t) ÷ (1+d)^t - Student Debt Salary Uplift
B(t) = B(t−1) × (1+r) − min(p × max(0, S(t) − T), B), net = Σ(S − paid − S_base) - Freelance Vs Employed Income
N_free = (rate × (1+g)^(t−1) × days − costs) × (1−τ_f), N_emp = S × (1−τ_e) + S × c - Relocation Salary Adjustment
surplus(t) = S × (1+g)^(t−1) − L × (1+c) × (1+i)^(t−1); advantage = Σ new − Σ stay − move cost - Commute Cost Time Value
cost(t) = (d × n + (m/60) × n × w) × (1+g)^(t−1); FV = Σ cash_t × (1+r)^(T−t) - Pay Rise Vs Inflation
r_real = (1+g)/(1+i) − 1, S_real(t) = S₀ × (1+g)^(t−1) ÷ (1+i)^(t−1) - Pension Contribution Lifetime Value
F(t) = F(t−1) × (1+r) + S₀ × (1+g)^(t−1) × (c_e + c_r), F_real = F ÷ (1+i)^t - Side Income Replacement
I(t) = I₀ × (1+g)^(t−1); t* = 1 + ln(target ÷ I₀) ÷ ln(1+g) - Sabbatical Savings Drawdown
B(m) = B(m−1) × (1+r/12) − (spend × (1+i/12)^(m−1) − income)
Life planning
12 of 12 calculators shown- Cost Of Raising A Child
total = Σ (base + childcare_y) × (1 + i)^y, y = 0 … 18 − age - Wedding Savings Plan
D = (target − S₀(1+r)^n) × r / [(1+r)^n − 1] - New Baby First Year Budget
total = birth + gear + Σ(supplies + childcare_m) + Σ income_lost_m - Pet Lifetime Cost
lifetime = setup + Σ annual × (1 + i)^(y−1), y = 1 … L - Car Ownership Total Cost
TCO = (P − P(1−d)^n) + n × (insurance + fuel + maintenance) - Home Maintenance Reserve
Rᵧ = Rᵧ₋₁(1 + r) + V₀(1 + a)^(y−1) × p − repairᵧ - Family Net Worth Projection
NWᵧ = [Aᵧ₋₁(1 + g) + S] − max(Dᵧ₋₁(1 + i) − P, 0) - Debt Free Date All Debts
Bₘ = Bₘ₋₁(1 + i) − payment, highest rate paid first - Inheritance Drawdown Plan
Bᵧ = Bᵧ₋₁(1 + r) − W₀(1 + g)^(y−1) - Charitable Giving Plan
Dᵧ = I₀(1 + g)^(y−1) × p; net = D × (1 − c) - Travel Fund Big Trip
target = C₀(1 + f)^n; D = (target − S₀(1+r)^n) × r / [(1+r)^n − 1] - Second Home Affordability
net = 12 × P(1−d)·r(1+r)ⁿ/[(1+r)ⁿ−1] + carrying − rent