FIRE Calculator
Estimate your FIRE number and see how savings, spending, returns, and withdrawal rate affect your path to financial independence. Use target age mode to solve for the monthly contribution you would need.
Scenario 1
Build your base FIRE plan here. Scenario 2 and Scenario 3 can compare alternative paths against it.
Scenario 2
Turn this on when you want to compare a second path against your baseline plan.
Scenario 3
Add a third comparison path when you want to pressure-test one more alternative.
Results
$900,000
$3,000
54.2
24.2
$36,000
FIRE chart
Portfolio value versus the FIRE number over time, using real returns.
Want to understand the math?
How to interpret this result
A FIRE calculation is built around one question: can your portfolio support your expected spending?
The result depends mostly on three numbers:
- Your FIRE number — the portfolio needed to support your annual spending.
- Your savings rate — how quickly you move toward that number.
- Your withdrawal rate — how much of the portfolio you expect to use each year in retirement.
The output is a planning estimate, not a retirement guarantee.
What to watch
Spending
Spending drives the FIRE number directly. If expected retirement spending goes up, the required portfolio goes up with it.
Withdrawal rate
A 4% withdrawal rate means you need about 25 times annual spending. A 3.5% rate is more conservative and requires a larger portfolio.
Real return
This calculator uses inflation-adjusted returns. That keeps portfolio growth and retirement spending in the same purchasing-power terms.
Current savings
Money already invested has more time to compound. A larger starting portfolio can move the FIRE date earlier even if monthly contributions stay the same.
Target age mode
If you already have a target retirement age, use target age mode. It shows whether the required monthly contribution is realistic.
A simple way to use this calculator
Start with your base case, then run two stress tests:
- lower expected return by 1–2%
- reduce the withdrawal rate from 4% to 3.5%
- increase expected retirement spending by 10–20%
If the plan only works in the optimistic case, the target may need more margin.
Related reading
Methodology
Want the formulas and assumptions?
FAQ
What is a FIRE number?
Your FIRE number is the estimated portfolio needed to support your annual spending. A common starting formula is annual spending divided by withdrawal rate.
Is the 4% rule guaranteed?
No. It is a historical planning reference, not a guarantee. Longer retirements may require a lower withdrawal rate.
Why does spending matter so much?
Because spending affects both sides of the plan. Lower spending reduces the portfolio you need and may increase how much you can save.
Should I use real or nominal returns?
For FIRE planning, real returns are usually clearer because retirement spending is about purchasing power.
What is target age mode for?
Target age mode starts with a retirement age and solves for the monthly contribution needed to reach it.
Does this calculator include market risk?
Not directly. It uses average return assumptions. Test lower-return scenarios to see how fragile the plan is.