FIRE calculator
Your FIRE number is your yearly spending divided by the withdrawal rate you trust. At 4%, that is 25 times what you spend in a year. This calculator works out that number, then projects your savings in today's money to show how many years it may take to get there.
Your result
FIRE number
900,000
25× your yearly spending
Time to financial independence
About 21.3 years (between 16.9 and 30.4 years)
- Saved each month
- 2,000
- Savings rate
- 40%
- Return after inflation
- 3.9%
| Return after inflation | years | |
|---|---|---|
| Return 3 points higher | 6.9% | 16.9 |
| Your return | 3.9% | 21.3 |
| Return 3 points lower | 0.9% | 30.4 |
How the calculation works
FIRE number = monthly spending × 12 ÷ withdrawal rate. The idea comes from William Bengen's 1994 study of historical US returns and the 1998 Trinity study, which found that withdrawing about 4% of a stock and bond portfolio in the first year, then adjusting for inflation, lasted 30 years in most historical periods. Retirements longer than 30 years usually call for a lower rate.
The projection runs on your real return, not the nominal one, because the target is in today's money. Real return uses the Fisher formula: (1 + return) ÷ (1 + inflation) − 1. Subtracting inflation from the return gives the wrong figure, and the error grows as inflation rises: a 10% return with 3% inflation is a 6.8% real return, not 7%.
Each month your savings grow at the monthly equivalent of that real return, (1 + yearly rate)^(1/12) − 1, and the difference between your income and spending is added at the end of the month. The calculator runs the same projection with your return 3 percentage points lower and 3 points higher, because no one knows the return in advance. That is why the result is a range, not a single date.
It leaves out taxes, pensions, one-off expenses and changes in spending. Treat the result as a scenario based on your own assumptions, not a forecast.
Common questions
What is a FIRE number?
It is the amount of invested money that could cover your current spending indefinitely at a chosen withdrawal rate. With a 4% rate it equals 25 times your yearly spending: someone spending 36,000 a year needs 900,000.
Is the 4% rule safe?
It held for 30-year retirements in most historical US periods, which is what the original studies tested. For a retirement of 40 years or more, or a portfolio with less in stocks, many people plan with 3 to 3.5%. You can enter any rate here and see how the target changes.
Should I enter the return before or after inflation?
Enter the nominal return and your inflation estimate separately. The calculator combines them with the Fisher formula, so you do not have to work out the real return yourself.
Why does it show a range instead of one date?
Returns are uncertain, and a few points of difference over decades moves the date by years. The range shows the same plan with a return 3 points lower and 3 points higher than the one you entered.
Does it include taxes or a state pension?
No. If you expect a pension, you can subtract it from your monthly spending to see how much your portfolio still needs to cover.
Track the number you are saving toward
TrackYourInvestment keeps your stocks, funds, gold, crypto and cash in one place, in one currency, and has the same FIRE calculator built in, fed by your real portfolio value.
This calculator is for education and planning. It is not investment, tax or retirement advice, and past returns do not guarantee future ones.