FIRE number calculator
Your FIRE number is the amount that could cover your yearly spending through withdrawals. Enter your spending and a withdrawal rate to get the target, then add what you have saved and what you add each year to estimate how long it takes.
Runs in your browser: nothing you enter is sent anywhere.
How to use it
- Enter what you spend in a year and the withdrawal rate you want to plan with.
- Enter what you have invested, how much you add each year and the return you expect after inflation.
- Read the target, your progress and the estimated years.
How it works
- FIRE number = yearly spending ÷ withdrawal rate.
- Years to reach it solve savings × (1 + r)^n + yearly × ((1 + r)^n − 1) ÷ r = target for n. With a 0% return it is simply (target − saved) ÷ yearly.
Worked example
Spending 40,000 a year at a 4% withdrawal rate gives a FIRE number of 1,000,000, which is 25 times your spending. With 250,000 saved, 50,000 added each year and a 5% return, the target is reached in about 9.6 years.
Tips
- A lower withdrawal rate gives a larger, safer target; a higher one gives a smaller, riskier one.
- Cutting spending helps twice: it lowers the target and raises the amount you can save.
- This is a planning aid, not financial advice.
Frequently asked questions
How is the FIRE number calculated?
It is yearly spending divided by the withdrawal rate. At 4% that is spending × 25, so 40,000 a year needs 1,000,000.
What is the 4% rule?
It is a rule of thumb that you could withdraw about 4% of a portfolio in the first year and adjust that amount for inflation afterwards. It is a rough guide, not a guarantee, and people choose lower rates for longer retirements.
Why use a return after inflation?
The calculator works in today's money. If you enter a return after inflation, the target and the years to reach it stay in today's purchasing power.
Does the estimate include taxes or changing spending?
No. Spending is treated as a fixed yearly amount and taxes are not modelled, so treat the result as a starting point for planning.