How to use the FIRE calculator
- Enter what you spend in a year and what you earn after tax. The difference is what you can invest.
- Add what you have invested and a return after inflation. Because everything is in today's money, your spending does not need to rise with prices.
- Pick a withdrawal rate. 4 % is the classic; 3.5 % is safer for retirements longer than 30 years.
- Read your number and date, plus the Lean, regular and Fat FIRE targets and your Coast FIRE point.
The FIRE number
At 4 % that is 25 times your yearly spending. The time to get there depends mostly on your savings rate, the share of your income you invest. Someone saving 10 % needs about 40 years or more; someone saving 50 % can get there in roughly 15 to 17 years at a 5 % real return.
Lean, Fat and Coast FIRE
- Lean FIRE: a frugal budget, here 70 % of your current spending.
- Fat FIRE: a generous budget, here 150 % of your spending.
- Coast FIRE: you have invested enough that, without adding a cent, growth alone reaches your number by 65. From then on you only need to earn what you spend.
Example
Sam spends 36,000 a year and earns 60,000 after tax, so invests 24,000 a year: a 40 % savings rate. The FIRE number is 36,000 ÷ 4 % = 900,000. Starting from 40,000 at a 5 % real return, Sam gets there in about 20 years, around age 50.
More: the 4 % rule explained.
Frequently asked questions
Is 4 % safe?
It held for 30-year retirements in most of US history, but early retirees may need money for 40 or 50 years. Many use 3.25 to 3.5 % for extra safety, or stay flexible and spend less after bad market years.
What about health care and pensions?
Add expected health costs to your yearly spending. A later state pension lowers what your savings must cover, so your real number may be smaller.
Sources: Bengen W. (1994), Journal of Financial Planning; Cooley, Hubbard and Walz (1998), "Retirement Savings: Choosing a Withdrawal Rate That Is Sustainable" (the Trinity study). Illustrations only, not advice.
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Last reviewed: 2026-11-08. Results are estimates based on the returns you enter, not advice. See our disclaimer.