★ MONEY · RETIREMENT · ANNUITY
$609,985.50 from $500 a month — $180,000.00 paid in, $429,985.50 of growth. At 7% for 30 years, $500 a month grows to $609,985.50, pays $4,729.21 a month for 20 years, or $2,033.28 a month on the 4% rule. Enter your numbers to work out yours.
An annuity here is a steady monthly contribution that compounds: every month you put money in, and every month the whole balance earns the monthly return. This calculator works out the future value, the total paid in, the interest earned, the monthly payout over 20 years, and the 4% rule — with the monthly contribution, the annual return, the years, and the starting lump sum you choose.
An annuity here is a steady monthly contribution that compounds: every month you put money in, and every month the whole balance earns the monthly return. The monthly rate is the annual return divided by 12, and the number of months is the years times 12. The future value is the monthly contribution times the growth factor — the factor is one plus the monthly rate to the power of the months, minus one, divided by the monthly rate — plus the lump sum grown at the same rate for the same months. Contributions are made at the end of each month, so the first contribution earns one month less than the full term. The total paid in is the monthly contribution times the months, plus the lump sum. The interest earned is the future value minus the total paid in. The monthly payout is what the future value pays out over 20 years at the same rate: the future value times the monthly rate, divided by one minus one plus the monthly rate to the power of minus 240. The 4% rule is the future value times 4% a year, divided by 12 for the monthly figure — a rough guide to a sustainable withdrawal, not a promise.
At the defaults — $500 a month, annual return 7%, 30 years, lump sum $0 — the future value is $609,985.50, the total paid in is $180,000.00, and the interest earned is $429,985.50. That pot pays $4,729.21 a month for 20 years at the same rate, or $2,033.28 a month ($24,399.42 a year) on the 4% rule. Growth supplies more than twice what you put in: $500 a month for 30 years is only $180,000 of your own money.
| Case | Future value | Paid in | Interest | Payout/mo | 4% rule/mo |
|---|---|---|---|---|---|
| Default ($500/mo, 7%, 30 yr, $0 lump) | $609,985.50 | $180,000.00 | $429,985.50 | $4,729.21 | $2,033.28 |
| Monthly contribution $250 | $304,992.75 | $90,000.00 | $214,992.75 | $2,364.61 | $1,016.64 |
| Monthly contribution $750 | $914,978.25 | $270,000.00 | $644,978.25 | $7,093.82 | $3,049.93 |
| Monthly contribution $1,000 | $1,219,971.00 | $360,000.00 | $859,971.00 | $9,458.42 | $4,066.57 |
| Annual return 5% | $416,129.32 | $180,000.00 | $236,129.32 | $2,746.27 | $1,387.10 |
| Annual return 9% | $915,371.74 | $180,000.00 | $735,371.74 | $8,235.84 | $3,051.24 |
| 10 years | $86,542.40 | $60,000.00 | $26,542.40 | $670.96 | $288.47 |
| 20 years | $260,463.33 | $120,000.00 | $140,463.33 | $2,019.37 | $868.21 |
| 40 years | $1,312,406.70 | $240,000.00 | $1,072,406.70 | $10,175.08 | $4,374.69 |
| Initial lump sum $10,000 | $691,150.47 | $190,000.00 | $501,150.47 | $5,358.48 | $2,303.83 |
Setup: monthly contribution $500, annual return 7%, 30 years, lump sum $0.
Line 1 — the monthly rate and the months. The monthly rate is 7% ÷ 12 = 0.5833% a month (0.005833), and the months are 30 × 12 = 360.
Line 2 — the growth factor. The factor is ((1.005833)360 − 1) ÷ 0.005833 = 1,219.97. Every dollar a month becomes $1,219.97 after 30 years at 7%.
Line 3 — the future value. $500 × 1,219.97 = $609,985.50. The lump sum is $0, so it adds nothing.
Line 4 — the total paid in and the interest. $500 × 360 = $180,000.00 paid in, so the interest is $609,985.50 − $180,000.00 = $429,985.50. Growth supplies $429,985.50 of the $609,985.50 — more than twice what you put in.
Line 5 — the monthly payout. Spreading $609,985.50 over 20 years at the same 7% gives $4,729.21 a month, or $1,135,010.66 over the 20 years — the pot keeps earning while you draw it down. On the 4% rule the same pot gives $2,033.28 a month, $24,399.42 a year, and the pot should last far longer than 20 years.
Reverse: to reach $500,000 in 30 years at 7% you need $409.85 a month (forward: $500,000.00); to reach $1,000,000 you need $819.69 a month; to reach $250,000 you need $204.92 a month. At $500 a month it takes 27.53 years (330.41 months; 331 months gives $502,001.25) to reach $500,000, and 36.38 years to reach $1,000,000. The return needed for $500,000 at $500 a month over 30 years is 5.9764%; for $1,000,000 it is 9.4222%.
Monthly contribution $250: the future value is $304,992.75, exactly half the default — the future value scales in direct proportion to the contribution when the rate and years stay fixed. You pay in $90,000.00 and growth supplies $214,992.75. The payout is $2,364.61 a month.
Monthly contribution $750: the future value is $914,978.25, you pay in $270,000.00, and growth supplies $644,978.25. The payout is $7,093.82 a month, and the 4% rule gives $3,049.93 a month.
Monthly contribution $1,000: the future value is $1,219,971.00 — exactly twice the default — you pay in $360,000.00 and growth supplies $859,971.00. The payout is $9,458.42 a month. Doubling the contribution doubles the pot, but it does not double the years you need: time does the heavy lifting.
Annual return 5%: the future value is $416,129.32, with $236,129.32 of interest. Two points off the return costs $193,856.18 of future value — the return matters more than the contribution once the pot is large.
Annual return 9%: the future value is $915,371.74, with $735,371.74 of interest. Two points above the default adds $305,386.24. The payout is $8,235.84 a month. Small differences in return compound into large differences in outcome.
10 years: the future value is $86,542.40, you pay in $60,000.00, and growth supplies only $26,542.40. Ten years is too short for compounding to do much: most of the pot is your own money.
20 years: the future value is $260,463.33, you pay in $120,000.00, and growth supplies $140,463.33 — growth has overtaken your contributions by year 20. The payout is $2,019.37 a month.
40 years: the future value is $1,312,406.70, you pay in $240,000.00, and growth supplies $1,072,406.70 — more than four times what you put in. The last ten years add $702,421.20 to the pot. The payout is $10,175.08 a month. Starting ten years earlier is worth more than doubling the contribution.
Initial lump sum $10,000: the future value is $691,150.47 — the $10,000 lump grows to $81,164.97 on its own over 30 years at 7%, adding $81,164.97 to the default pot. You pay in $190,000.00 in total and growth supplies $501,150.47.
Reverse — the other way round: saving $409.85 a month reaches $500,000 in 30 years at 7%; $819.69 a month reaches $1,000,000; $204.92 a month reaches $250,000. At $500 a month it takes 27.53 years to reach $500,000 and 36.38 years to reach $1,000,000. The return needed for $500,000 is 5.9764%, and for $1,000,000 it is 9.4222%.
The model assumes the return is steady every year, contributions are made at the end of each month, the return compounds monthly, and there are no fees, taxes, or withdrawals before the end. It assumes the payout is drawn monthly over exactly 20 years at the same rate, and the 4% rule is a rough guide, not a guarantee. It does not know what the market will actually return: 7% is a long-run average for a diversified stock portfolio, not a promise for any single 30-year stretch. With a 0% return the future value is $180,000.00 — exactly what you paid in, with $0.00 of interest. With no contributions and a $10,000 lump sum the future value is $81,164.97 ($10,000.00 paid in, $71,164.97 of interest). With 0 years and a $10,000 lump sum the future value is $10,000.00. With 1 year the future value is $6,196.29 ($6,000.00 paid in, $196.29 of interest). Rounding convention: all figures are computed from unrounded values and rounded only for display — money to cents, rates to four decimals, so a figure worked out from the rounded numbers can differ by a few cents from the figure shown.
| Output | Formula | What it means |
|---|---|---|
| Future value | contribution × growth factor + lump sum × (1+i)n | $609,985.50. |
| Total paid in | contribution × months + lump sum | $180,000.00. |
| Interest earned | future value − total paid in | $429,985.50. |
| Monthly payout (20 years) | future value × i ÷ (1 − (1+i)−240) | $4,729.21/mo ($1,135,010.66 over 20 years). |
| 4% rule per month | future value × 4% ÷ 12 | $2,033.28/mo. |
| 4% rule per year | future value × 4% | $24,399.42/yr. |
| Growth factor | ((1+i)n − 1) ÷ i | 1,219.97. |
| Monthly saving for $500,000 | the contribution that reaches $500,000 in 30 years at 7% | $409.85/mo. |
| Monthly saving for $1,000,000 | the contribution that reaches $1,000,000 in 30 years at 7% | $819.69/mo. |
| Monthly saving for $250,000 | the contribution that reaches $250,000 in 30 years at 7% | $204.92/mo. |
| Years to $500,000 | the time for $500 a month at 7% to reach $500,000 | 27.53 years (330.41 months; 331 months gives $502,001.25). |
| Years to $1,000,000 | the time for $500 a month at 7% to reach $1,000,000 | 36.38 years (436.52 months; 437 months gives $1,003,029.58). |
| Rate needed for $500,000 | the return that turns $500 a month into $500,000 in 30 years | 5.9764%. |
| Rate needed for $1,000,000 | the return that turns $500 a month into $1,000,000 in 30 years | 9.4222%. |
| 0% return | same model, 0% return | Future value $180,000.00, interest $0.00. |
| No contributions, $10,000 lump | same model, $0 a month, $10,000 lump | Future value $81,164.97, paid $10,000.00, interest $71,164.97. |
| 0 years, $10,000 lump | same model, 0 years | Future value $10,000.00. |
| 1 year | same model, 1 year | Future value $6,196.29, paid $6,000.00, interest $196.29. |
| Monthly contribution $250 | same model, $250 a month | FV $304,992.75, paid $90,000.00, interest $214,992.75, payout $2,364.61/mo. |
| Monthly contribution $750 | same model, $750 a month | FV $914,978.25, paid $270,000.00, interest $644,978.25, payout $7,093.82/mo. |
| Monthly contribution $1,000 | same model, $1,000 a month | FV $1,219,971.00, paid $360,000.00, interest $859,971.00, payout $9,458.42/mo. |
| Annual return 5% | same model, 5% return | FV $416,129.32, paid $180,000.00, interest $236,129.32, payout $2,746.27/mo. |
| Annual return 9% | same model, 9% return | FV $915,371.74, paid $180,000.00, interest $735,371.74, payout $8,235.84/mo. |
| 10 years | same model, 10 years | FV $86,542.40, paid $60,000.00, interest $26,542.40, payout $670.96/mo. |
| 20 years | same model, 20 years | FV $260,463.33, paid $120,000.00, interest $140,463.33, payout $2,019.37/mo. |
| 40 years | same model, 40 years | FV $1,312,406.70, paid $240,000.00, interest $1,072,406.70, payout $10,175.08/mo. |
| Initial lump sum $10,000 | same model, $10,000 lump | FV $691,150.47, paid $190,000.00, interest $501,150.47, payout $5,358.48/mo. |
The math is exact for the numbers you enter: the future value is the monthly contribution times the growth factor plus the lump sum grown at the same rate, the total paid in is the contributions plus the lump sum, the interest is the difference, the payout spreads the pot over 20 years at the same rate, and the 4% rule is the pot times 4% a year. What the model cannot do is know the future: check the return, because 7% is a long-run average for a diversified stock portfolio, not a promise for any single 30-year stretch, and check the fees, because a 1% annual fee cuts the pot by far more than 1%. It assumes contributions at the end of each month, a steady return, monthly compounding, and no taxes or withdrawals before the end. It leaves out inflation — $609,985.50 in 30 years buys less than $609,985.50 today — and any employer match. For the lump sum alone, see future value calculator; for a monthly retirement target, see retirement savings calculator.
Bright Side Kit. "Annuity Calculator: Future Value, Payout & Income 2026" https://brightoolbox.com/annuity-calculator/ Accessed October 25, 2026.$609,985.50 at 7%. You pay in $180,000.00 and growth supplies $429,985.50. That pot pays $4,729.21 a month for 20 years, or $2,033.28 a month on the 4% rule.
$409.85 a month at 7% over 30 years. Forward-checked: $409.85 a month grows to exactly $500,000.00. For $1,000,000 you need $819.69 a month, and for $250,000 you need $204.92 a month.
27.53 years at 7%. That is 330.41 months; after 331 months the pot is $502,001.25. To reach $1,000,000 at the same pace takes 36.38 years.
5.9764% a year over 30 years. At that return $500 a month grows to exactly $500,000.00. For $1,000,000 the return needed is 9.4222% a year.
Starting earlier usually wins. $500 a month for 40 years grows to $1,312,406.70, while $1,000 a month for 30 years grows to $1,219,971.00 — the extra ten years beats doubling the contribution. The last ten years alone add $702,421.20 to the pot.
You get exactly what you put in. At 0% the future value is $180,000.00 — $500 a month for 360 months — with $0.00 of interest. A $10,000 lump sum with no contributions grows to $81,164.97 at 7% over 30 years, so the return is doing most of the work.