Starting at 40 with $10,000 and adding $500 a month at 5% a year gives $332,568 at 65. That balance supports about $1,109 a month under a 4% withdrawal rule of thumb.
What the projection assumes
The model starts with $10,000 saved, adds a fixed monthly contribution and applies a constant 5% yearly return until 65. It ignores inflation, taxes and fees, so treat the figures as a comparison between scenarios, not a forecast.
In the 25-year case you contribute $160,000 and growth adds $172,568.
Time is the lever
The same $500 a month grows to $154,782 over 15 years, $332,568 over 25 years and $625,383 over 35 years. Starting earlier raises the result more than the same increase in the monthly amount.
The table shows three contribution levels against three horizons.
From balance to income
A common rule of thumb is to withdraw about 4% of the balance a year. On $332,568 that is about $1,109 a month. It is an approximation, not a guarantee, and it does not include pensions or other income.
| Per month | 15 years | 25 years | 35 years |
|---|---|---|---|
| $250 | $87,959 | $183,690 | $341,360 |
| $500 | $154,782 | $332,568 | $625,383 |
| $1,000 | $288,426 | $630,323 | $1,193,430 |
FAQ
How much should I save each month?+
It depends on your target income and start age. Use the retirement calculator to test amounts; the table above shows how contribution and time combine.
Is the 4% rule reliable?+
It is a rule of thumb from historical data and not a guarantee. Your situation, markets and fees can change the outcome.