$400 a month for 20 years at returns from 4% to 10%
| Return | Balance | Of which growth | In today’s dollars |
|---|---|---|---|
| 4% | $145,537 | $49,537 | $80,580 |
| 5% | $162,322 | $66,322 | $89,874 |
| 6% | $181,375 | $85,375 | $100,423 |
| 7% | $203,015 | $107,015 | $112,404 |
| 8% | $227,600 | $131,600 | $126,016 |
| 10% | $287,304 | $191,304 | $159,073 |
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 |
| 4 | $19,200 | $21,987 | $19,535 |
| 5 | $24,000 | $28,478 | $24,566 |
| 6 | $28,800 | $35,424 | $29,667 |
| 7 | $33,600 | $42,856 | $34,846 |
| 8 | $38,400 | $50,808 | $40,108 |
| 9 | $43,200 | $59,316 | $45,461 |
| 10 | $48,000 | $68,421 | $50,911 |
| 11 | $52,800 | $78,162 | $56,466 |
| 12 | $57,600 | $88,586 | $62,132 |
| 13 | $62,400 | $99,739 | $67,917 |
| 14 | $67,200 | $111,673 | $73,829 |
| 15 | $72,000 | $124,442 | $79,875 |
| 16 | $76,800 | $138,105 | $86,062 |
| 17 | $81,600 | $152,724 | $92,401 |
| 18 | $86,400 | $168,367 | $98,898 |
| 19 | $91,200 | $185,105 | $105,563 |
| 20 | $96,000 | $203,015 | $112,404 |
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) |
|---|---|---|---|
| 10 years | $50,415 | $66,204 | $87,518 |
| 20 years | $122,546 | $189,615 | $301,108 |
The middle of the simulation sits below the steady 7% figure of $203,015 because ups and downs cost compounding: a 20% loss needs a 25% gain to get back.
What $203,015 would pay in retirement
At a 4% first-year withdrawal, $203,015 pays about $8,121 a year, $677 a month, before tax; in today’s dollars that is about $4,496 a year. How long a balance near it lasts at each withdrawal: how long $200,000 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 |
| 20 years | $203,015 | $112,404 |
| $400 a month for 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 20 years
$50 a month: $25,377, $100 a month: $50,754, $150 a month: $76,130, $200 a month: $101,507, $250 a month: $126,884, $300 a month: $152,261, $500 a month: $253,768, $600 a month: $304,522, $750 a month: $380,652, $1,000 a month: $507,536, $1,500 a month: $761,305, $2,000 a month: $1,015,073, $2,500 a month: $1,268,841, $3,000 a month: $1,522,609, $5,000 a month: $2,537,682.
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.