How to calculate your FIRE number
- Enter how much you expect to spend each year once you stop working, in today's money.
- Enter what you have invested now and how much you can invest each year.
- Set an expected real return (after inflation; 4–7% is a common range for a stock-heavy portfolio) and a safe withdrawal rate (4% is the classic rule).
- See your FIRE number, how many years until you reach it, and a growth chart. Try Lean and Fat FIRE to compare lifestyles, and share the link to save your plan.
The 4% rule and the FIRE number
FIRE stands for Financial Independence, Retire Early. Your FIRE number is the portfolio that can fund your spending indefinitely: annual spending ÷ withdrawal rate, which at 4% is 25 times your yearly expenses. 40,000 a year needs 1,000,000. The 4% figure comes from the 1998 "Trinity study" and William Bengen's research on historical US market returns, which found that a balanced portfolio survived 30-year retirements in most periods when withdrawing 4% of the starting value, adjusted for inflation. Early retirees with 40+ year horizons often use 3–3.5% to be safer.
The projection grows your savings once a year at the real return and adds your yearly investment. Working in real (inflation-adjusted) terms keeps everything in today's money. Your savings rate matters most: the more of your income you invest, the bigger the portfolio grows and the less you need to live on. This is a simplified model for planning conversations, not financial advice; returns are not smooth, and taxes, fees, healthcare and pensions all change the picture. Everything is calculated in your browser.
What is Lean FIRE and Fat FIRE?
Lean FIRE plans for a frugal budget; Fat FIRE for a more comfortable one. The buttons scale your spending by 0.7× and 1.5×.
Should I use a nominal or real return?
Real (after inflation), because spending and the FIRE number are in today's money.
Is 4% safe for early retirement?
For very long retirements, many planners suggest 3–3.5%, or flexible spending in bad years.