Retirement Withdrawal Calculator
Enter your retirement savings, expected return, inflation rate, and how many years you need the money to last. The calculator tells you the largest safe monthly withdrawal that draws your balance to zero at the end of that period. Switch to "How long will my money last?" mode to go the other way: enter a fixed monthly amount and find out exactly how many years your nest egg will hold out. All figures use inflation-adjusted real returns so the purchasing power of every dollar stays comparable across years.
How the retirement withdrawal calculator works
The calculator uses the present-value annuity formula to find the level monthly payment that exactly draws a lump sum (your nest egg) to zero over a given number of periods. The key formula is PMT = PV * r / (1 - (1 + r)^-n), where PV is your starting balance, r is the real monthly interest rate, and n is the number of monthly payments. The "real" rate is your nominal return adjusted for inflation using the Fisher equation: real rate = ((1 + nominal) / (1 + inflation)) - 1. Working in real terms means every figure already accounts for the eroding effect of inflation on purchasing power, so you do not need to manually adjust amounts year by year. In "How long will savings last?" mode the formula is inverted: n = -ln(1 - PV * r / PMT) / ln(1 + r), solving directly for the number of months your balance will last at a given monthly draw.
The 4% rule explained
The "4% rule" originated from research by financial planner William Bengen in 1994 and was later reinforced by the Trinity Study. The rule states that a retiree who withdraws 4% of their portfolio in the first year of retirement, and adjusts that amount for inflation each year, has historically been able to sustain withdrawals for at least 30 years regardless of market conditions. This benchmark was derived from US stock and bond market data going back to 1926, including periods like the Great Depression and stagflation of the 1970s. A 4% rate corresponds to a portfolio of 25 times annual expenses. It is a useful starting point, but not a guarantee: low expected returns, longer retirements (40+ years), or a heavier stock weighting can all push the safe rate down.
Withdrawal strategies compared
Fixed-dollar withdrawals (what this calculator solves for) are the simplest: the same dollar amount leaves the portfolio each month. Their downside is inflexibility - if the market falls sharply early in retirement, the fixed draw consumes a larger share of a smaller balance, a phenomenon called sequence-of-returns risk. Fixed-percentage withdrawals (e.g. 4% of whatever the current balance is each year) avoid depleting the portfolio entirely because the dollar amount shrinks when returns are bad, but they make budgeting harder. The "bucket strategy" splits savings into short-term (cash), medium-term (bonds), and long-term (stocks) buckets, drawing first from cash so equity positions are not sold during downturns. Dynamic or guardrail strategies adjust withdrawals based on portfolio performance, cutting spending when balances fall below a trigger level and allowing higher spending after strong years.
Taxes, Social Security, and other income sources
This calculator focuses on the portfolio withdrawal math and treats your nest egg as a single pool. In practice, withdrawals from traditional IRAs and 401(k) accounts are taxed as ordinary income, while Roth accounts are tax-free in retirement. Required Minimum Distributions (RMDs) force withdrawals from tax-deferred accounts starting at age 73, which may be larger or smaller than your optimal draw. Social Security and pension income reduce the amount you need to pull from savings - enter those amounts in the "Other monthly income" field to see your combined picture. A qualified tax advisor or fee-only financial planner can map the optimal order of account withdrawals (taxable, tax-deferred, tax-free) to minimize your lifetime tax burden.
Withdrawal rate safety benchmarks
| Annual rate | Label | Typical longevity |
|---|---|---|
| Below 3% | Very conservative | 35+ years (near-infinite) |
| 3.0% to 4.0% | Classic 4% rule zone | 25-35 years |
| 4.1% to 5.0% | Moderate risk | 20-25 years |
| 5.1% to 6.0% | Aggressive | 15-20 years |
| Above 6% | High depletion risk | Under 15 years |
Historical research suggests these annual withdrawal rate zones for a balanced (60% stock / 40% bond) portfolio.
Frequently asked questions
What is the 4% withdrawal rule?
The 4% rule is a retirement guideline stating that you can withdraw 4% of your portfolio in the first year of retirement, then adjust that amount for inflation each subsequent year, and historically have a very high probability of not running out of money for at least 30 years. It was first described by financial planner William Bengen in 1994 using US historical market returns. A 4% rate means you need a nest egg of 25 times your annual expenses. Some researchers now suggest 3.3% or lower as a more conservative benchmark for longer retirements in a low-return environment.
How long will $500,000 last in retirement?
It depends on your withdrawal rate, investment return, and inflation. At a 4% annual withdrawal rate ($20,000 per year, or about $1,667 per month) with a 6% nominal return and 2.5% inflation, $500,000 will last approximately 25-30 years. If you withdraw $3,000 per month ($36,000 per year, a 7.2% rate), the money runs out much faster - roughly 17-19 years under the same assumptions. Use the calculator above to model your specific numbers.
What is a safe retirement withdrawal rate?
For a 30-year retirement with a balanced 60/40 portfolio, historical research points to 3.5% to 4.0% as a safe withdrawal rate. For longer retirements (35-40+ years) or if expected returns are low, many planners suggest 3.0% to 3.5%. Higher rates of 5% or more increase the risk of running out of money before you die, especially if a market downturn occurs in the first few years of retirement when the portfolio is at its largest.
Should I adjust withdrawals for inflation each year?
Yes. This calculator uses real (inflation-adjusted) returns so that the monthly withdrawal figure already reflects constant purchasing power. In practice, most retirees increase their nominal withdrawal by the previous year's inflation rate each January. If you use a fixed-percentage withdrawal strategy instead (taking a set percentage of the current balance each year), the amount fluctuates automatically with the portfolio but not necessarily with your actual cost of living.
How does Social Security affect my withdrawal calculation?
Social Security acts as a guaranteed income floor that reduces your dependence on portfolio withdrawals. If you expect $1,500 per month from Social Security and need $4,000 to live on, you only need your portfolio to cover $2,500 per month. Enter your monthly Social Security or pension benefit in the "Other monthly income" field to see how it changes the required portfolio withdrawal and how much longer your savings will last.
What is sequence-of-returns risk?
Sequence-of-returns risk is the danger that a string of bad investment returns early in retirement permanently damages your portfolio even if long-term average returns are fine. If your portfolio drops 30% in year one and you continue making fixed withdrawals, you deplete a much larger fraction of your reduced balance. The same average return earned in a different order - good years first - leaves far more intact. Strategies to manage it include keeping 1-2 years of expenses in cash, using a bucket approach, or reducing withdrawals temporarily when the portfolio is down more than 20%.