Markets don't return the average every year. This runs 1,000 random scenarios to estimate the chance your money lasts.
How this is calculated Embed on your siteUpdated October 2026
A simple retirement projection assumes the same return every year. Real markets don't work that way, and the order of good and bad years matters a great deal once you are withdrawing money. This calculator runs your plan through 1,000 different market paths and counts how many make it to the end. With the defaults, $750,000 supporting $45,000 a year (6% of savings, rising with inflation) lasts 30 years in only 19% of the simulations. Cut the withdrawal to $30,000, the classic 4%, and the success rate rises to 67%.
Each year in each of the 1,000 paths, the portfolio earns a random return drawn around your average return, with swings set by the volatility you enter. Your withdrawal comes out and then rises with inflation the next year. If the balance hits zero before the last year, that path fails. The success rate is the share of paths that last. The same inputs always produce the same 1,000 paths, so you can compare scenarios fairly.
$750,000 over 30 years, 6% average return, 12% volatility, 3% inflation:
| Withdrawal in year one | Share of savings | Success rate | Median balance left |
|---|---|---|---|
| $22,500 | 3.0% | 91% | $1,304,704 |
| $26,250 | 3.5% | 81% | $870,484 |
| $30,000 | 4.0% | 67% | $498,427 |
| $33,750 | 4.5% | 54% | $137,660 |
| $37,500 | 5.0% | 44% | $0 |
And how the length of retirement matters, at a 4% withdrawal: 93% success over 20 years, 82% over 25, 67% over 30, 52% over 35 and 44% over 40.
The 4% rule came from testing withdrawals against actual U.S. stock and bond returns since 1926, which averaged well above the 6% nominal return used as the default here. With a 6% return and 3% inflation, your money earns only about 3% after inflation, so a 4% withdrawal is a stretch. Raise the average return to 7% and the 4% withdrawal succeeds 80% of the time; a 3% withdrawal succeeds 95% of the time. The point is not which number is "right" but how sensitive the result is to your assumptions. Use a return you would be comfortable defending.
Many planners aim for 80% to 90%, not 100%. A plan that succeeds in every simulation usually means you are spending less than you could. A plan below about 70% is fragile. The success rate also assumes you never adjust, and real retirees do: cutting spending by 10% after a bad market year is often enough to rescue a plan that the simulation counts as a failure.
For a quick deterministic estimate, try the retirement withdrawal calculator. To set the savings target in the first place, use the FIRE calculator.
It tests a retirement plan against many randomly generated market histories instead of one average return, then reports the share in which the money lasts. This shows how much luck in market timing can affect the outcome.
Many planners target 80% to 90%. Higher than that often means you could spend more; much lower means the plan depends heavily on good markets.
Roughly 10% to 12% for a balanced stock and bond portfolio, 15% to 18% for an all-stock portfolio. Higher volatility lowers the success rate at the same average return.
It reflects the default assumptions: a 6% average return with 3% inflation. Historical U.S. returns were higher, which is why the 4% rule held up in past tests. At a 7% average return, the same plan succeeds 80% of the time here.
Only if you never change course. In practice, spending a bit less after bad years or adding income can keep a plan on track.
Returns are drawn from a normal distribution around your average return with the volatility you enter; withdrawals rise with inflation each year; 1,000 paths per run. Educational estimate, not financial advice.