FIRE Number Calculator
Find your FIRE number from yearly spending and a safe withdrawal rate, and how many years of saving it takes to reach financial independence.
Your FIRE number — FIRE stands for Financial Independence, Retire Early — is a savings target based on your planned yearly spending and an assumed withdrawal rate. This calculator estimates the target and the years of saving needed to reach it. A withdrawal rate is a planning assumption, not a guarantee that a portfolio will last for life.
How to use this tool
- Enter what you expect to spend each year once you stop working.
- Choose a withdrawal rate: 4% is the classic figure, while 3–3.5% is more cautious for retirements longer than 30 years.
- Enter your invested savings now, how much you invest each year and an expected return after inflation.
- Add your age to see the age at which you could reach financial independence.
Formula
FIRE number = yearly spending ÷ withdrawal rate
At 4% that is 25 × yearly spending. Years to get there: n = ln((F + S/R) ÷ (B + S/R)) ÷ ln(1 + R), where F is the FIRE number, B your current savings, S the amount you invest each year (added at year end) and R the real annual return. At 0% return, n = (F − B) ÷ S. Fractional years interpolate the annual model; a negative return can make the target unreachable.
Example
Spending $40,000 a year at a 4% withdrawal rate gives a FIRE number of $1,000,000. With $100,000 invested, $25,000 added every year and a 5% real return, n = ln(1,500,000 ÷ 600,000) ÷ ln(1.05) ≈ 18.8 years, so a 30-year-old would reach financial independence at about 48.8. You are 10% of the way there today.
Frequently asked questions
Why use a return after inflation?
Your spending will rise with prices. Using a real return — for example a 7% expected return minus 2–3% inflation — keeps every figure in today's dollars, so the FIRE number does not need adjusting later.
Is 4% safe for early retirees?
The 4% rule comes from back-tests of 30-year retirements in US market history. Someone stopping work at 40 may need their money to last 50 years or more, so many early retirees plan on 3.25–3.5%, which raises the target to roughly 29–31 times spending.
What spending should I include?
Everything you will pay for yourself: housing, food, transport, travel, taxes on withdrawals and especially health insurance before Medicare at 65. Leave out costs that will end, such as a mortgage you will have paid off.
Sources
This tool gives an estimate for general information only. It is not financial, tax, legal or medical advice — check with a qualified professional before you rely on the result.
Last updated: 2026-10-30