Safe Withdrawal Rate Calculator

Each year the balance grows at your return and you withdraw the rate × the starting corpus, increased by inflation. Solve mode finds the rate that leaves your target balance after N years; test mode runs your rate and reports the ending balance — or the year it runs dry.

What a safe withdrawal rate is

A withdrawal rate is the slice of your starting corpus you take in the first year — then you raise that amount with inflation each year to keep your spending power. The “safe” rate is the largest one your money survives for the whole retirement. The famous 4% rule is just one instance of this: on a 30-year horizon with historical market returns, withdrawing 4% (rising with inflation) tended to last. This calculator generalises it to your own corpus, horizon, return and inflation.

Worked example — $1,000,000, 30-year retirement, 5% return, 2.5% inflation, depleting to zero: The safe rate is about 4.6% — roughly $46,000 in year one. Test the 4% rule on the same plan and it survives comfortably, leaving about $585,000 after 30 years.

Solve it, or test a rate

Two ways to use it. “Find the safe rate” solves for the maximum sustainable percentage given your inputs — the answer to “what can I take?”. “Test a rate” takes a figure you have in mind (say the 4% rule, or a higher number you’re hoping for) and shows whether it lasts, the ending balance if it does, and the year it runs dry if it doesn’t. The balance chart makes survival obvious: a curve that stays above zero lasts; one that dives to the axis fails.

Horizon, and deplete vs preserve

Two levers move the safe rate a lot. The longer the retirement, the lower the rate — a 50-year early retirement needs a meaningfully smaller percentage than a 30-year one, which is why FIRE planners often use 3–3.5%. And your goal for the money matters: depleting to zero allows the highest rate, while preserving your capital (keeping its real value intact, so you could leave it to heirs or fund a longer life) requires a much lower rate — closer to your real return.

The big caveat

This uses a single, constant return every year. That’s clean, but it hides sequence-of-returns risk — the real reason the 4% rule has a safety margin. A market crash in the first few years of retirement, when the balance is largest and you’re withdrawing, does far more harm than the same crash later. The original 4% research used actual historical sequences, including bad ones, to find a rate that survived them. So treat a rate that only just survives here with caution, and lean conservative.