Wire Voltage Drop
Calculator
Results
- Voltage drop (V)
- 6.6048
- Voltage drop (%)
- 2.871652
- Loop resistance (Ω)
- 0.4128
- Power lost in the cable (W)
- 105.6768
- Voltage drop with aluminium (V)
- 10.8288
Electrical results
| Voltage drop (V) | 6.6048 |
| Voltage drop (%) | 2.871652 |
| Loop resistance (Ω) | 0.4128 |
| Power lost in the cable (W) | 105.6768 |
| Voltage drop with aluminium (V) | 10.8288 |
formula-map diagram
- Voltage drop (V)
- 6.6048
- Voltage drop (%)
- 2.871652
- Loop resistance (Ω)
- 0.4128
- Power lost in the cable (W)
- 105.6768
- Voltage drop with aluminium (V)
- 10.8288
Electrical relationship
Formula
ΔV = 2 × ρ × L × I / A (ρ_Cu = 0.0172 Ω·mm²/m)= 6.6048
Note
This is a simplified model: it applies the textbook relationship to the numbers you entered and assumes ideal components, steady-state sinusoidal conditions, balanced loads and copper resistivity of 0.0172 Ω·mm²/m at 20 °C. It ignores component tolerances, temperature drift, skin effect, harmonics, inrush, transformer and battery losses, and it is not a substitute for the wiring code that applies where you are. Have any installation sized and verified by a licensed electrician or engineer.
More in Electrical engineering
See all →Frequently asked questions
How is voltage drop in a wire calculated?+
Vdrop = I x R, where R is the total resistance of the wire run (both directions, if it's a round trip) based on its gauge, length, and material. Wire resistance is usually looked up per unit length from a wire table and scaled to your actual run length.
Why does wire length matter so much for voltage drop?+
Resistance is directly proportional to length, so doubling the distance from source to load doubles the wire's resistance and therefore doubles the voltage drop for the same current — this is why long runs need thicker wire.
What's an acceptable voltage drop percentage?+
A common guideline is to keep voltage drop under about 3% for branch circuits and under 5% total from source to the farthest load, though some codes and equipment have their own tighter requirements — always check applicable electrical code for your situation.
Does voltage drop only matter for long wire runs?+
It's most noticeable on long runs, but high-current circuits can see significant drop even over short distances, since drop depends on both current and resistance together, not length alone.
How do I fix an excessive voltage drop?+
The main options are using a thicker (lower gauge number) wire, which lowers resistance, or shortening the run if possible. Increasing supply voltage or reducing load current can also help but usually aren't practical mid-project.