About the FIRE Calculator
This FIRE calculator answers the two core questions of the Financial Independence, Retire Early movement: how much do I need, and how long will it take? Your FIRE number is the portfolio that can pay your annual expenses indefinitely at a safe withdrawal rate — 25 times expenses at the classic 4% rule.
Enter your current investments and how much you save each year, and the calculator projects your portfolio month by month at a real (after-inflation) return until it reaches your FIRE number. You get the years to financial independence, your FIRE age, your savings rate, and lean and fat FIRE targets for comparison.
Using a real return keeps the FIRE number in today’s dollars, which fixes a common mistake of comparing an inflated future balance against today’s spending. Contributions are spread evenly across each month; returns are an assumed steady average. The projection runs for up to 70 years — if your plan does not reach the FIRE number in that time, the years and age show as never reached rather than a made-up figure.
With the default inputs, the your fire number is $1,250,000.00. Change any value above to recalculate instantly.
How to use the fire calculator
- 1Enter your age and your annual expenses in today’s dollars.
- 2Add your current invested assets and how much you invest each year.
- 3Set your expected return and inflation.
- 4Choose a safe withdrawal rate — 4% is classic, 3%–3.5% is more cautious.
- 5Read your FIRE number, years to FIRE and FIRE age, then test higher savings.
Formula and method
Your FIRE number divides annual expenses by the safe withdrawal rate. At 4% that equals 25 × expenses; at 3.5% it is about 28.6 ×. The portfolio is then projected monthly: each month it earns the monthly equivalent of the real return and one-twelfth of your yearly savings is added.
Years to FIRE is the number of months until the balance reaches the FIRE number, divided by 12. Lean FIRE uses 70% of your expenses (a frugal budget) and fat FIRE 150% (a more comfortable one), both at the same withdrawal rate.
- E
- Annual expenses in today’s dollars
- SWR
- Safe withdrawal rate
- S
- Amount invested per year
- r
- Nominal annual return
- π
- Inflation
Worked examples
Spending $50k, $150k invested, saving $40k a year
At 4% you need 25 × $50,000 = $1.25 million, and you have 12% of it. Investing $40,000 a year at a real return of about 3.88% gets you there in about 17.2 years, at age 47.
Lean FIRE budget at 3.5%
A $30,000 budget at a 3.5% withdrawal rate needs about $857,000. Saving $30,000 a year with a real return near 4.85% reaches it in about 17.5 years, at 42½.
Savings too low to reach FIRE
With a 3% return and 3% inflation the real return is zero, so $1,000 a year builds only $70,000 in 70 years — far short of the $1.5 million target. The calculator reports that FIRE is never reached.
Frequently asked questions
What is a FIRE number?+
Your FIRE number is the invested amount that can cover your annual expenses indefinitely. It is usually annual expenses divided by the safe withdrawal rate — 25 × expenses at 4%.
What is the 4% rule?+
The 4% rule, from US studies of historical returns, found that withdrawing 4% of a stock/bond portfolio in year one and then adjusting for inflation survived nearly all 30-year periods. Longer early retirements often use 3.25%–3.5%.
What are lean FIRE and fat FIRE?+
Lean FIRE means retiring on a minimal budget, often under $40,000 a year for a household, while fat FIRE means a comfortable budget, often $100,000 or more. The calculator shows both at 70% and 150% of your expenses.
Why does my savings rate matter so much?+
A higher savings rate both adds more to your portfolio and implies lower expenses, which shrinks the FIRE number. Going from a 20% to a 50% savings rate can cut the time to FIRE by decades.
Should I include Social Security?+
Many FIRE planners ignore it for safety. If you include it, reduce the expenses your portfolio must cover after the age benefits start, or use the full retirement calculator.
Results are estimates for educational purposes and are not financial advice. Rates, fees and terms vary — confirm with your lender or a licensed advisor before making decisions.