Retirement Withdrawal Calculator
Test any withdrawal rate against thousands of simulated retirements, or solve for the highest rate that still clears your target success bar — the real "will my money last" question, done honestly.
Each simulated year draws a return from your mean and volatility, applies it to the balance, then subtracts that year's withdrawal — $40Kin year 1, increased with inflation every year after (the standard "4% rule" definition), never reduced back down if markets fall. Reproducible seed: 42.
Why this may look lower than the famous "4% rule":that figure comes from studies that replay actual historical decades, which have some mean-reversion baked in. This tool draws each year's return independently at random, which has no memory of the year before — a stricter, more conservative test that can show a lower safe rate for the same assumptions. Neither is more "correct"; they answer slightly different questions. Educational only, not financial advice.
The 4% rule, tested honestly
The "4% rule" says: withdraw 4% of your starting balance in year one of retirement, then raise that dollar amount with inflation every year after, and a 30-year retirement historically held up. It comes from replaying real historical decades — which, unlike random draws, have some mean-reversion baked in. Run the same 4%, 30-year case here with a 7% expected return and 15% volatility, and 5,000 independently-randomized paths succeed 70% of the time — lower than the headline figure, because this model has no memory of the year before. It is a stricter test, not a wrong one.
Ask a different question — what withdrawal rate clears a 90% success bar under these same assumptions? — and the answer here is 2.79%, not 4%. That gap is the entire point of running your own numbers instead of borrowing someone else's rule of thumb.
How it works
Pick a mode. Test a withdrawal rate runs your chosen rate through thousands of simulated retirements and reports the probability it never runs out. Find my safe rateinstead binary-searches for the highest rate that still clears a success bar you choose (90%, 95%, whatever you consider "safe enough"). Every year draws a random return from your mean and volatility, compounds the balance, then subtracts that year's withdrawal — the starting rate applied to your original balance, then escalated with inflation every year, never re-based to a shrunken portfolio.
Honest limitation: independent yearly draws with no mean-reversion are a stricter, more conservative test than historical-sequence studies like the original 4% rule — expect this tool to run more conservative than headlines you may have seen elsewhere. Educational only, not financial advice; consult a professional before making retirement decisions.
Keep going
For a general-purpose growth simulation (saving, not withdrawing), use the Monte Carlo simulator. For the straight-line version without randomness, the compound interest calculator.
Common questions
What is the 4% rule?
A rule of thumb from 1990s research: withdraw 4% of your starting portfolio in year one of retirement, then increase that dollar amount with inflation every year after, and a typical 30-year retirement historically survived. It is a starting point, not a guarantee — the "safe" rate depends heavily on your actual returns, volatility, and time horizon.
What is a safe withdrawal rate?
The highest withdrawal rate that still lets your money last through retirement at an acceptable probability — commonly 90% or 95% of simulated outcomes never running out. It is not one fixed number; it moves with your expected return, volatility, retirement length, and how much risk of failure you are willing to accept.
Why might this tool show a different number than the 4% rule?
The original 4% rule comes from replaying actual historical decades, which have some mean-reversion baked in — a few bad years are often followed by a recovery. This simulator draws each year’s return independently at random with no memory of the year before, a stricter test that can produce a more conservative safe rate for the same assumptions. Both are legitimate ways to study the question; they are just not the same question.
What happens if I withdraw too much?
The simulation tracks every simulated retirement separately. If a path’s balance hits zero, it stays at zero — that path is counted as having "run out of money," even if it would have kept compounding on paper. The percentage of paths that never hit zero is the success probability.