What this calculator does
Find out how many years your retirement savings will last, and how much you could take out each year. Once you start living on savings, the big question flips. It's no longer how much to save, but how much you can safely take out.
The calculator runs your balance forward one year at a time. It takes your withdrawal at the start of each year and grows what's left at the return you expect. Then it raises the next withdrawal with inflation, so your spending power stays the same. It tells you how many years the money lasts, to a tenth of a year.
It also works the problem backward. Tell it how many years the money needs to last. It finds the largest first-year withdrawal that would use up the balance exactly at the end. It shows that as a withdrawal rate, so you can compare it with the well-known 4% rule of thumb.
Where it's used
Why this math matters outside the classroom:
- Retirement budgeting. A retiree with $1,000,000 checks whether taking $45,000 a year, rising 2.5% yearly, lasts the 30 years she plans for.
- Choosing a withdrawal rate. Planners find the first-year withdrawal that empties a balance in exactly 30 years and compare it with the 4% rule of thumb.
- Endowment payouts. Small trusts test a fixed yearly payout against an assumed return to see how many years the fund can keep paying.
- Geometric series in class. Students sum the series 1 + q + q² + … to turn a stream of rising payments into the lump sum that funds them.
Grade level and standards: Grades 11–12; Common Core State Standards for Mathematics HSA.SSE.B.4. © Copyright 2010. National Governors Association Center for Best Practices and Council of Chief State School Officers. All rights reserved.
How to use it
- Enter the balance you'll draw from and the amount you plan to take in the first year.
- Enter the yearly return you expect on the money that stays invested, after fees. Then enter the inflation rate used to raise each year's withdrawal.
- Enter how many years the money should last, for example to age 95.
- Read how long the money lasts, what's left at the end of your plan and the sustainable withdrawal. Then check the year-by-year table.
What the inputs mean
- First-year withdrawal
- The first year's amount, before tax. Each later year rises by the inflation rate, which keeps your spending power level.
- Yearly return
- The average yearly return on the invested balance, after fees. A balanced retirement mix of investments is usually expected to earn less than one that's all stocks.
- Years the money should last
- How long a retirement you want to pay for. It sets the ending balance shown, the length of the table and the sustainable withdrawal.
Formula and method
withdrawal in year k: wₖ = W × (1 + g)^k, k = 0, 1, 2, … each year: balance = (balance − wₖ) × (1 + r) years lasted = full years + remaining balance ÷ that year's withdrawal initial withdrawal rate = W ÷ starting balance × 100 sustainable W* = B ÷ Σ qᵏ (k = 0 … N − 1), with q = (1 + g) ÷ (1 + r)
W is the first-year withdrawal. g is the inflation rate and r is the yearly return, both as decimals (2.5% is 0.025). k counts the years, starting from 0, and wₖ is the withdrawal in year k.
Each year the withdrawal comes out first, and what's left earns that year's return. At some point the balance may be smaller than a full year's withdrawal. Then the share of that year it covers is added to the count of years.
For the sustainable withdrawal W*, B is the starting balance and N is the number of years. All N rising withdrawals, valued in today's dollars, must add up to the balance. Each withdrawal grows by (1 + g) and is shrunk back to today's value by (1 + r). So each one is q times the one before.
Σ means "add up": here, all the values of qᵏ from year 0 to year N − 1. Dividing the balance by that sum gives the first-year amount that empties the account exactly at the end of year N.
Worked example
You retire with $1,000,000 and plan to take $45,000 in the first year. You'll raise it 2.5% a year for inflation. You expect a 5% yearly return and want the money to last 30 years.
- Initial withdrawal rate: $45,000 ÷ $1,000,000 × 100 = 4.5%.
- Each year: (balance − withdrawal) × 1.05, with the withdrawal 2.5% larger than the year before.
- After 31 full years only $24,657.64 is left, less than that year's $96,750.30 withdrawal: 31 + 24,657.64 ÷ 96,750.30 ≈ 31.25 years.
- Balance after the planned 30 years: about $117,874.01.
- Sustainable first-year withdrawal for 30 years: $1,000,000 ÷ 21.616147 = $46,261.71, a 4.63% rate.
Result: The money lasts about 31.2 years, with $117,874.01 left after 30 years. You could start as high as $46,261.71 a year and still last exactly 30 years with these assumptions.
Understanding the result
If the money lasts longer than your planned years, the plan has a cushion. The ending balance shows how big it is.
If the money runs out first, compare your withdrawal with the sustainable one. The difference is roughly how much you'd need to trim from the first year's spending.
The return is fixed, so treat the answer as one possible future. Run it again with a return one or two points lower to see how sensitive the plan is. Poor returns early in retirement are the main risk to any withdrawal plan.
Assumptions and limitations
- The withdrawal is taken at the start of each year. The rest earns the return for the full year.
- One steady return and one inflation rate for every year.
- Withdrawals rise with inflation every year and are never skipped or cut.
- No taxes, required minimum distributions (withdrawals the law makes you take from some accounts) or fees beyond those in the return.
- This is an educational estimate, not financial advice. Real returns vary from year to year. The order of good and bad years can shorten or stretch how long savings last.
- Taxes on withdrawals aren't included. Neither is other income such as Social Security or pensions. So enter only the part of your spending your savings must cover.
- Results beyond 100 years are shown as more than 100 years.
Frequently asked questions
What is the 4% rule?
It's a rule of thumb. You withdraw 4% of your balance in the first year of retirement, then raise that dollar amount with inflation. It comes from studies of past US market returns over 30-year retirements. Enter your own numbers here to see how it plays out under your assumptions.
Why does the money last longer than balance ÷ withdrawal?
Because the money you haven't withdrawn keeps earning a return. With a 5% return and 2.5% inflation, a 4.5% starting rate lasts over 31 years. That's far longer than the 22 years a simple division would suggest.
Should I enter the return before or after inflation?
Use the return before inflation is taken out, the figure you'd usually see quoted. That's because the calculator already raises each withdrawal with the inflation rate you enter. If you'd rather work in today's dollars, enter a real return (after inflation) and set inflation to 0.
What is the sustainable withdrawal rate?
It's the first-year withdrawal, as a share of the starting balance, that would leave exactly nothing at the end of your chosen number of years. It uses the return and inflation you entered. It's a planning figure, not a guarantee.
Does withdrawing monthly change much?
A little. Taking money monthly leaves more invested for part of each year. So the money lasts slightly longer than with one withdrawal at the start of the year. The yearly method used here is a little cautious.
How this calculator is checked
Method: Year-by-year drawdown with start-of-year withdrawals indexed to inflation; present value of a growing annuity-due (geometric series) for the sustainable withdrawal. The calculation is covered by automated tests with known reference values and edge cases. Last updated 2026-10-18. Found a problem? Tell us.
Embed this calculator
Put this Retirement Withdrawal Calculator on your own website or blog for free. Paste this code where you want it to appear: