$400 a month for 25 years at returns from 4% to 10%
| Return | Balance | Of which growth | In today’s dollars |
|---|---|---|---|
| 4% | $203,539 | $83,539 | $97,211 |
| 5% | $234,294 | $114,294 | $111,900 |
| 6% | $270,516 | $150,516 | $129,200 |
| 7% | $313,217 | $193,217 | $149,594 |
| 8% | $363,596 | $243,596 | $173,656 |
| 10% | $493,330 | $373,330 | $235,617 |
Year by year at 7%
| Year | Put in so far | Balance | In today’s dollars |
|---|---|---|---|
| 1 | $4,800 | $4,952 | $4,808 |
| 2 | $9,600 | $10,251 | $9,662 |
| 3 | $14,400 | $15,921 | $14,570 |
| 5 | $24,000 | $28,478 | $24,566 |
| 10 | $48,000 | $68,421 | $50,911 |
| 15 | $72,000 | $124,442 | $79,875 |
| 20 | $96,000 | $203,015 | $112,404 |
| 25 | $120,000 | $313,217 | $149,594 |
The range in 1,000 simulated markets
A 7% average does not arrive as 7% every year. In 1,000 simulated sequences of returns averaging 7% with 12% volatility, this is where $400 a month ended up: 1 in 10 markets finished below the first figure, half below the middle one, and 1 in 10 above the last.
| After | Weak (1 in 10 lower) | Middle | Strong (1 in 10 higher) |
|---|---|---|---|
| 13 years | $68,782 | $96,378 | $135,023 |
| 25 years | $172,985 | $292,128 | $490,863 |
The middle of the simulation sits below the steady 7% figure of $313,217 because ups and downs cost compounding: a 20% loss needs a 25% gain to get back.
What $313,217 would pay in retirement
At a 4% first-year withdrawal, $313,217 pays about $12,529 a year, $1,044 a month, before tax; in today’s dollars that is about $5,984 a year. How long a balance near it lasts at each withdrawal: how long $300,000 lasts. To stop saving early and let growth do the rest, see Coast FIRE numbers by age.
$4,800 a year fits in an IRA, whose 2026 limit is $7,500 under 50. See contribution limits, the 401(k) calculator and the Roth IRA calculator.
$400 a month for other terms
| Years | Balance | In today’s dollars |
|---|---|---|
| $400 a month for 5 years | $28,478 | $24,566 |
| $400 a month for 10 years | $68,421 | $50,911 |
| $400 a month for 15 years | $124,442 | $79,875 |
| $400 a month for 20 years | $203,015 | $112,404 |
| 25 years | $313,217 | $149,594 |
| $400 a month for 30 years | $467,781 | $192,720 |
| $400 a month for 35 years | $684,565 | $243,283 |
| $400 a month for 40 years | $988,617 | $303,067 |
Other amounts for 25 years
$50 a month: $39,152, $100 a month: $78,304, $150 a month: $117,456, $200 a month: $156,608, $250 a month: $195,760, $300 a month: $234,913, $500 a month: $391,521, $600 a month: $469,825, $750 a month: $587,281, $1,000 a month: $783,042, $1,500 a month: $1,174,563, $2,000 a month: $1,566,084, $2,500 a month: $1,957,605, $3,000 a month: $2,349,126, $5,000 a month: $3,915,209.
How it is worked out
Monthly amounts are deposited at the end of each month and compounded monthly at the rate that equals the annual return; lump sums compound once a year. The headline return is 7% a year, the Trinity-style average the site’s retirement pages use; stock-heavy portfolios have averaged more over long periods and bond-heavy ones less, which is why every page shows 4% to 10%. Today’s dollars divide by 3% inflation a year. The range comes from 1,000 simulated sequences of yearly returns averaging 7% with 12% volatility, with each year’s deposits added through the year. Fees and taxes are not taken out. More on the methodology page.