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FIRE calculator
Your FIRE number and the age you get there, for lean, regular and fat FIRE.
With $40,000 a year of spending and a 4% withdrawal rate, your FIRE number is $1,000,000. Starting at 35 with $100,000 invested and $25,000 saved a year at 5% after inflation, you reach it at 53.8. Put in your own numbers to see your date.
FIRE number
$1,000,000
$40,000 a year ÷ 4% withdrawal rate. At your saving rate you reach it in 18.8 years.
Amounts are in today's dollars.
| Goal | Spending a year | Portfolio needed | Reached in | Age |
|---|---|---|---|---|
| Lean FIRE | $25,000 | $625,000 | 12.9 years | 47.9 |
| FIRE | $40,000 | $1,000,000 | 18.8 years | 53.8 |
| Fat FIRE | $100,000 | $2,500,000 | 33.0 years | 68.0 |
| Coast FIRE by 65 | $40,000 | $231,377 today | 6.2 years | 41.2 |
Chart data
| Age | Portfolio (today's dollars) |
|---|---|
| 35 | $100,000 |
| 40 | $265,769 |
| 45 | $477,337 |
| 50 | $747,357 |
| 55 | $1,091,979 |
| 58 | $1,342,914 |
How the FIRE calculator works
Your FIRE number is the portfolio that pays for a year of spending at your withdrawal rate:
FIRE number = annual spending ÷ withdrawal rate
At 4% that is 25 times your spending, so $40,000 a year needs $1,000,000. The years until you get there come from the growth of what you have invested now plus what you add each year:
Years = ln((F × r + S) ÷ (P × r + S)) ÷ ln(1 + r)
F is the FIRE number, P what you have invested now, S what you save each year and r the return after inflation. With the example values ($100,000 invested, $25,000 a year, 5% real) that gives 18.8 years: age 53.8 for someone who is 35 today.
Lean and fat FIRE use the same formulas and the same assumptions with a different budget, so the three results can be compared directly. With the example values, lean FIRE ($25,000 a year) arrives at 47.9 and fat FIRE ($100,000 a year) at 68.0.
How the withdrawal rate changes it
A lower withdrawal rate is more cautious and needs a bigger portfolio: at 3.5%, $40,000 a year needs $1,142,857. The table of FIRE numbers by spending and withdrawal rate shows the rest. The 4% figure comes from studies of US market history over retirements of up to about 30 years. Research on longer retirements, such as the Early Retirement Now safe withdrawal rate series, finds that horizons of 40 years or more call for lower rates.
Real or nominal returns: why it changes the answer
The calculator works in today's dollars, so the return must be the return after inflation (real). If you think in returns before inflation (nominal), choose "Before inflation" and the calculator converts them with the exact Fisher formula:
Real return = (1 + nominal) ÷ (1 + inflation) − 1
A 7% return with 3% inflation is 3.88% real, slightly less than the 4% you get by subtracting. Typing 7% into a calculator that expects a real return is an easy mistake to make: with the example values it shows financial independence in 16.1 years instead of 20.8 years, about 4.7 years too early.
These results are illustrations from the numbers you enter, not forecasts. Real markets do not return the same amount every year, and taxes, fees and the order of good and bad years all change the outcome. See the disclaimer.
Assumptions and limits
- Everything is in today's dollars. Your yearly saving is assumed to rise with inflation.
- The return is the same every year. Real portfolios vary, and a bad run of years early in retirement matters more than the average.
- Savings are added at the end of each year. Fractional years are interpolated, so round up if you invest once a year.
- Taxes and investment fees are not included. Enter your spending including the taxes you expect to pay on withdrawals.
- Social Security, pensions and part-time income are not included. Any income you will have in retirement lowers the portfolio you need.
- The 4% studies looked at fixed horizons with no fees or taxes; early retirement can last much longer.
Four mistakes that move your FIRE number
- Mixing nominal and real. Entering a 7% nominal return as if it were real made the example look 4.7 years shorter than it is.
- Using 4% for a very long retirement. At 3.5%, $40,000 a year needs $1,142,857 instead of $1,000,000: $142,857 more.
- Leaving out taxes. If 15% of each withdrawal went to tax, spending $40,000 would need withdrawals of $47,059 and a FIRE number of $1,176,471.
- Counting a home you live in. The portfolio is what you can sell to pay for spending; a home you live in does not pay for groceries.
Related
Coast FIRE calculator: how much you need invested today to stop saving and still reach this FIRE number later. Net worth by age calculator: where your net worth sits among US families your age. Methodology: every formula and default, and how the calculators are tested.
Sources
- William P. Bengen, "Determining Withdrawal Rates Using Historical Data", Journal of Financial Planning, October 1994.
- Philip L. Cooley, Carl M. Hubbard and Daniel T. Walz, "Retirement Savings: Choosing a Withdrawal Rate That Is Sustainable", AAII Journal, February 1998 (the Trinity study).
- Mr. Money Mustache, "The Shockingly Simple Math Behind Early Retirement", January 13, 2012: the 5% real return used as the example here.
- U.S. Bureau of Labor Statistics, Consumer Price Index, for US inflation history.
Last reviewed by Asier Fernández, editor, on . Educational information only, not financial advice. How we calculate