$150 a month for 10 years at returns from 4% to 10%
| Return | Balance | Of which growth | In today’s dollars |
|---|---|---|---|
| 4% | $22,004 | $4,004 | $16,373 |
| 5% | $23,154 | $5,154 | $17,229 |
| 6% | $24,371 | $6,371 | $18,134 |
| 7% | $25,658 | $7,658 | $19,092 |
| 8% | $27,019 | $9,019 | $20,104 |
| 10% | $29,980 | $11,980 | $22,308 |
Year by year at 7%
| Year | Put in so far | Balance | In today’s dollars |
|---|---|---|---|
| 1 | $1,800 | $1,857 | $1,803 |
| 2 | $3,600 | $3,844 | $3,623 |
| 3 | $5,400 | $5,970 | $5,464 |
| 4 | $7,200 | $8,245 | $7,326 |
| 5 | $9,000 | $10,679 | $9,212 |
| 6 | $10,800 | $13,284 | $11,125 |
| 7 | $12,600 | $16,071 | $13,067 |
| 8 | $14,400 | $19,053 | $15,041 |
| 9 | $16,200 | $22,244 | $17,048 |
| 10 | $18,000 | $25,658 | $19,092 |
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 $150 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) |
|---|---|---|---|
| 5 years | $8,712 | $10,522 | $12,810 |
| 10 years | $18,905 | $24,827 | $32,819 |
The middle of the simulation sits below the steady 7% figure of $25,658 because ups and downs cost compounding: a 20% loss needs a 25% gain to get back.
What $25,658 would pay in retirement
At a 4% first-year withdrawal, $25,658 pays about $1,026 a year, $86 a month, before tax; in today’s dollars that is about $764 a year. How long a balance near it lasts at each withdrawal: how long $100,000 lasts. To stop saving early and let growth do the rest, see Coast FIRE numbers by age.
$1,800 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.
$150 a month for other terms
| Years | Balance | In today’s dollars |
|---|---|---|
| $150 a month for 5 years | $10,679 | $9,212 |
| 10 years | $25,658 | $19,092 |
| $150 a month for 15 years | $46,666 | $29,953 |
| $150 a month for 20 years | $76,130 | $42,152 |
| $150 a month for 25 years | $117,456 | $56,098 |
| $150 a month for 30 years | $175,418 | $72,270 |
| $150 a month for 35 years | $256,712 | $91,231 |
| $150 a month for 40 years | $370,731 | $113,650 |
Other amounts for 10 years
$50 a month: $8,553, $100 a month: $17,105, $200 a month: $34,210, $250 a month: $42,763, $300 a month: $51,316, $400 a month: $68,421, $500 a month: $85,526, $600 a month: $102,631, $750 a month: $128,289, $1,000 a month: $171,052, $1,500 a month: $256,578, $2,000 a month: $342,103, $2,500 a month: $427,629, $3,000 a month: $513,155, $5,000 a month: $855,259.
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.