Coast FIRE Calculator

Coast FIRE is the point where the money you've already invested will grow — on its own, with no further contributions — into enough to retire on by your target age. After that, your job only needs to cover today's living costs, not future retirement savings.

This calculator is for anyone who wants to know two things: how big their retirement portfolio ultimately needs to be (the FIRE number), and whether they've already saved enough to coast to it.

Current invested savings is money already working for retirement. Annual expenses is what you expect to spend per year in retirement, in today's dollars. The expected return should be a real (after-inflation) figure — around 5–7% is a common assumption for a diversified portfolio.

The safe withdrawal rate sets your FIRE number: at 4%, you need 25x your annual expenses. A lower rate is more conservative and produces a larger target.

Suppose you spend $40,000 a year, so at a 4% withdrawal rate your FIRE number is $1,000,000. You're 30, plan to retire at 60, and expect a 7% real return. Over 30 years, money grows about 7.6x, so you'd need roughly $131,000 invested today to coast to $1,000,000 — no additional saving required.

If you have less than that today, the calculator shows the shortfall; if you have more, you've already reached Coast FIRE.

Real returns are never constant, the 4% rule is a guideline rather than a guarantee, and this model ignores taxes, fees, and future contributions. Treat the result as a planning estimate, not a promise.