$50 a month for 20 years at returns from 4% to 10%
| Return | Balance | Of which growth | In today’s dollars |
|---|---|---|---|
| 4% | $18,192 | $6,192 | $10,073 |
| 5% | $20,290 | $8,290 | $11,234 |
| 6% | $22,672 | $10,672 | $12,553 |
| 7% | $25,377 | $13,377 | $14,051 |
| 8% | $28,450 | $16,450 | $15,752 |
| 10% | $35,913 | $23,913 | $19,884 |
Year by year at 7%
| Year | Put in so far | Balance | In today’s dollars |
|---|---|---|---|
| 1 | $600 | $619 | $601 |
| 2 | $1,200 | $1,281 | $1,208 |
| 3 | $1,800 | $1,990 | $1,821 |
| 4 | $2,400 | $2,748 | $2,442 |
| 5 | $3,000 | $3,560 | $3,071 |
| 6 | $3,600 | $4,428 | $3,708 |
| 7 | $4,200 | $5,357 | $4,356 |
| 8 | $4,800 | $6,351 | $5,014 |
| 9 | $5,400 | $7,415 | $5,683 |
| 10 | $6,000 | $8,553 | $6,364 |
| 11 | $6,600 | $9,770 | $7,058 |
| 12 | $7,200 | $11,073 | $7,767 |
| 13 | $7,800 | $12,467 | $8,490 |
| 14 | $8,400 | $13,959 | $9,229 |
| 15 | $9,000 | $15,555 | $9,984 |
| 16 | $9,600 | $17,263 | $10,758 |
| 17 | $10,200 | $19,091 | $11,550 |
| 18 | $10,800 | $21,046 | $12,362 |
| 19 | $11,400 | $23,138 | $13,195 |
| 20 | $12,000 | $25,377 | $14,051 |
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 $50 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 | $6,302 | $8,276 | $10,940 |
| 20 years | $15,318 | $23,702 | $37,638 |
The middle of the simulation sits below the steady 7% figure of $25,377 because ups and downs cost compounding: a 20% loss needs a 25% gain to get back.
What $25,377 would pay in retirement
At a 4% first-year withdrawal, $25,377 pays about $1,015 a year, $85 a month, before tax; in today’s dollars that is about $562 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.
$600 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.
$50 a month for other terms
| Years | Balance | In today’s dollars |
|---|---|---|
| $50 a month for 5 years | $3,560 | $3,071 |
| $50 a month for 10 years | $8,553 | $6,364 |
| $50 a month for 15 years | $15,555 | $9,984 |
| 20 years | $25,377 | $14,051 |
| $50 a month for 25 years | $39,152 | $18,699 |
| $50 a month for 30 years | $58,473 | $24,090 |
| $50 a month for 35 years | $85,571 | $30,410 |
| $50 a month for 40 years | $123,577 | $37,883 |
Other amounts for 20 years
$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, $400 a month: $203,015, $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.