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Formula
Each month B = (B − W) × (1 + i), with i = (1 + R)^(1/12) − 1 and W raised by inflation once a year; the maximum withdrawal is W = B₀ ÷ Σ (1 + π)^y × (1 + i)^−(12y + m) over every month of the period
- B
- the balance, updated once a month
- B₀
- the starting balance
- W
- the monthly withdrawal in the current year (a yearly amount is split into 12 equal parts)
- R
- the expected annual return as a decimal (5% = 0.05)
- i
- the monthly return that compounds to R over 12 months
- π
- the yearly inflation increase applied to withdrawals (0 if not adjusted)
- y, m
- the year (0, 1, 2 …) and month within the year (0 to 11) of each withdrawal
What the retirement withdrawal calculator answers
Once you stop working, the question changes from “how much will I have?” to “how long will it last?” This retirement withdrawal calculator has two modes:
- How long will my money last? Enter your savings, a monthly or yearly withdrawal and an expected return. The calculator tells you how many years and months the money lasts and, if you enter the age when withdrawals start, the age when it runs out.
- How much can I withdraw? Enter your savings and the number of years the money must last. The calculator finds the largest withdrawal that runs the balance down to zero at the end of that period.
Both modes can raise withdrawals with inflation each year, and both show a year-by-year table of the starting balance, withdrawals, investment growth and ending balance. The results are estimates under a steady return, not financial advice; real returns vary and are not guaranteed.
How long will my money last in retirement?
The table shows how long $500,000 lasts with withdrawals raised 3% a year for inflation.
| Monthly withdrawal (first year) | 3% return | 5% return | 7% return |
|---|---|---|---|
| $2,000 | 21 years, 1 month | 27 years | 42 years, 7 months |
| $2,500 | 16 years, 10 months | 20 years, 4 months | 27 years |
| $3,000 | 14 years | 16 years, 4 months | 20 years, 1 month |
| $3,500 | 12 years | 13 years, 8 months | 16 years, 1 month |
Two patterns stand out. A small cut in spending can add years, especially at higher returns. And when the return only matches inflation, as in the 3% column, the money lasts roughly the balance divided by the yearly withdrawal: $500,000 ÷ $24,000 is about 21 years.
Inflation adjustment matters a great deal. With a level $3,000 a month that never rises, the same $500,000 lasts 23 years and 1 month at a 5% return, compared with 16 years and 4 months when the withdrawal rises 3% a year.
How much can I withdraw each month?
The second mode works the other way around. Here is the largest first-year monthly withdrawal from $500,000, rising 3% a year, that lasts exactly the number of years shown.
| Money should last | 4% return | 6% return |
|---|---|---|
| 20 years | $2,321.28 | $2,772.13 |
| 25 years | $1,900.76 | $2,364.52 |
| 30 years | $1,620.96 | $2,097.36 |
| 35 years | $1,421.57 | $1,910.38 |
At a 4% return over 30 years, the first-year withdrawal is about $19,452, a withdrawal rate of roughly 3.9%. That is close to the 4% rule that came out of a 1998 study by three Trinity University professors, which tested inflation-adjusted withdrawals against historical U.S. stock and bond returns and found that 3% to 4% usually lasted 30 years. A plan that must last 35 years or more needs a lower starting withdrawal.
How to calculate retirement withdrawals by hand
With level withdrawals (no inflation adjustment), there is a closed-form answer. Take $250,000, withdrawing $2,000 at the start of each month, with a 4% annual return.
- Monthly return: i = 1.04^(1/12) − 1 ≈ 0.0032737.
- Balance × i: $250,000 × 0.0032737 ≈ $818.43.
- Withdrawal × (1 + i): $2,000 × 1.0032737 ≈ $2,006.55.
- Number of months: n = −ln(1 − 818.43 ÷ 2,006.55) ÷ ln(1.0032737) = −ln(0.592118) ÷ 0.0032684 ≈ 160.34.
- That is 160 full withdrawals, or 13 years and 4 months, followed by a final partial withdrawal of about $678.
When withdrawals rise with inflation there is no simple formula for the length, so the retirement withdrawal calculator simulates the balance month by month instead.
Year-by-year withdrawals and interest
The retirement withdrawal calculator puts a table under each result that shows every year of retirement: the balance at the start, the total withdrawn, the investment growth earned and the balance at the end. Early on, growth can nearly match the withdrawals, so the balance falls slowly. As the balance shrinks, growth shrinks with it, and the decline speeds up in the final years. If you plan to spend more in early retirement, run the calculator for that period, then start a second run from the remaining balance.
Common mistakes
- Assuming a steady return. The order of returns matters once you are withdrawing. Losses in the first few years, when the balance is largest, do more damage than the same losses later. Test a lower return to build in a margin.
- Ignoring inflation. Level withdrawals look as if they last much longer, but the money buys less each year.
- Forgetting taxes. Withdrawals from traditional retirement accounts are generally taxable, so the amount you can spend is lower than the amount you withdraw.
- Setting and forgetting. Revisit your withdrawal each year and adjust if returns or expenses change.
To see whether your savings are on track before you retire, use the retirement calculator. For pure growth without withdrawals, the compound interest calculator shows how a balance builds over time.
Worked examples
Monthly income rising with inflation
$750,000 at retirement, withdrawing $3,800 a month (raised 2.5% a year for inflation) from age 66, with a 5% annual return.
Inputs (How long will my money last?): Retirement savings = $750000; Withdrawal amount = $3800; Withdrawal frequency = Monthly; Expected annual return = 5 %; Raise withdrawals with inflation each year = Yes; Expected inflation = 2.5 %; Age when withdrawals start = 66 years
Monthly withdrawal = $3,800.00, raised 2.5% each year Monthly return i = (1 + 5%)^(1/12) − 1 = 0.4074% Each month: balance − withdrawal, then × (1 + i), until the balance runs out Result: 254 full withdrawals = 21 years, 2 months, then a final $4,483.03
Answer: Withdrawing $3,800.00 a month (rising 2.5% a year) from $750,000.00 at a 5% return lasts about 21 years, 2 months, to about age 87. This is an estimate; returns are not guaranteed.
A fixed yearly withdrawal
$320,000 with a level $28,000 a year (paid as $2,333.33 a month), not adjusted for inflation, at a 4% return.
Inputs (How long will my money last?): Retirement savings = $320000; Withdrawal amount = $28000; Withdrawal frequency = Yearly (paid in 12 monthly parts); Expected annual return = 4 %; Raise withdrawals with inflation each year = No
Monthly withdrawal = $28,000.00 ÷ 12 = $2,333.33 Monthly return i = (1 + 4%)^(1/12) − 1 = 0.3274% Each month: balance − withdrawal, then × (1 + i), until the balance runs out Result: 181 full withdrawals = 15 years, 1 month, then a final $1,237.32
Answer: Withdrawing $2,333.33 a month from $320,000.00 at a 4% return lasts about 15 years, 1 month. This is an estimate; returns are not guaranteed.
The most you can take for 25 years
$480,000 that should last 25 years at a 4.5% return, with withdrawals raised 3% a year.
Inputs (How much can I withdraw?): Retirement savings = $480000; Money should last = 25 years; Expected annual return = 4.5 %; Show the withdrawal as = Monthly amount; Raise withdrawals with inflation each year = Yes; Expected inflation = 3 %
Monthly return i = (1 + 4.5%)^(1/12) − 1 = 0.3675% Withdrawals at the start of each month, raised 3% each year, for 300 months W = $480,000.00 ÷ (present value of $1 withdrawn on that schedule) = $1,931.25 a month
Answer: $480,000.00 at a 4.5% return supports about $1,931.25 monthly, rising 3% a year, for 25 years. This is an estimate; returns are not guaranteed.
Edge case: withdrawals below the growth
$500,000 at a 6% return with a level $1,500 a month, below the $2,421.99 a month that the balance can pay out without shrinking.
Inputs (How long will my money last?): Retirement savings = $500000; Withdrawal amount = $1500; Withdrawal frequency = Monthly; Expected annual return = 6 %; Raise withdrawals with inflation each year = No
Monthly withdrawal = $1,500.00 Monthly return i = (1 + 6%)^(1/12) − 1 = 0.4868% Each month: balance − withdrawal, then × (1 + i), until the balance runs out
Answer: Withdrawing $1,500.00 a month from $500,000.00 at a 6% return, the money never runs out. This is an estimate; returns are not guaranteed.
Assumptions and limitations
- Withdrawals are taken at the start of each month, and the rest of the balance then earns one month of return. A yearly withdrawal is paid in 12 equal monthly parts.
- The expected return is the same every year. Real returns vary, can be negative and are not guaranteed, and a run of poor years early in retirement shortens how long money lasts.
- With inflation adjustment on, the withdrawal rises by the inflation rate once a year, at the start of each new year.
- How long the money lasts counts full monthly withdrawals; any smaller final withdrawal is shown separately. Projections stop at 100 years.
- Taxes, required minimum distributions, fees and other income are not modeled. Results are estimates for planning, not financial advice.
Frequently asked questions
How long will my retirement savings last?
It depends on the balance, how much you withdraw, the return you earn and whether withdrawals rise with inflation. For example, $500,000 with $3,000 a month rising 3% a year lasts about 16 years and 4 months at a 5% return. Enter your own figures in the duration mode to see the exact length and the year-by-year balance.
How much can I withdraw monthly in retirement?
Choose the "How much can I withdraw?" mode, enter your savings, the number of years the money should last and an expected return. The calculator finds the largest first-year monthly withdrawal that runs the balance down to zero at the end of that period, rising with inflation if you choose.
How do you calculate a retirement withdrawal rate?
Divide the first year's withdrawals by the balance at the start of retirement. Withdrawing $36,000 in the first year from $800,000 is a 4.5% withdrawal rate. The calculator shows this rate with every result.
Should withdrawals be adjusted for inflation?
If you want your withdrawals to keep their purchasing power, yes. Prices rise over a long retirement, so a level withdrawal buys less each year. Adjusted withdrawals make the money run out sooner, which makes them the more cautious assumption.
Why does the money sometimes last indefinitely?
If withdrawals are level and smaller than the return the balance earns each month, the balance never shrinks. The calculator shows the largest monthly withdrawal that leaves the principal untouched. This holds only if the return is actually earned every year, which is never guaranteed.
Does the calculator include taxes or required minimum distributions?
No. Withdrawals from traditional IRAs and 401(k) plans are generally taxable income, and the IRS generally requires minimum distributions from age 73. Treat the results as pre-tax amounts and check that your planned withdrawal is at least your required minimum.
Sources
- Retirement Savings: Choosing a Withdrawal Rate That Is Sustainable — AAII Journal (the Trinity study). Checked October 10, 2026.
- Managing Your Retirement Portfolio — FINRA. Checked October 10, 2026.
- Retirement plan and IRA required minimum distributions FAQs — Internal Revenue Service. Checked October 10, 2026.
- Consumer Price Index — U.S. Bureau of Labor Statistics. Checked October 10, 2026.