About this tool
FIRE / Financial Independence Calculator is a free, in-browser tool that computes your FIRE number — the portfolio that lets you live off withdrawals indefinitely — and how many years of saving it will take to get there. All inputs stay on your device.
The FIRE number is annual expenses divided by your safe withdrawal rate (SWR): at the classic 4% rule that is 25× expenses; at a more conservative 3.5% it is about 28.6×. Years to independence are found by iterating your net worth forward — each year it grows by the expected return and your annual savings are added — until it reaches the target.
Use it to see how cutting expenses attacks the problem from both sides: lower spending shrinks the target and raises your savings rate at the same time, which is why expenses dominate the years-to-FI math.
Frequently asked questions
What is the 4% rule?
A guideline from the Trinity study: withdrawing 4% of a diversified portfolio in year one (inflation-adjusted after) historically survived 30-year retirements. Your FIRE number at 4% is therefore expenses ÷ 0.04 = 25× annual spending; lower the SWR for a longer or safer retirement.
How are years to FI computed?
By simulation: net worth is multiplied by (1 + return) and this year's savings are added, repeating until the FIRE number is reached. Use an inflation-adjusted (real) return like 5–7% so the target stays in today's money.
What if the target is never reached?
If growth plus savings can't reach the FIRE number within 200 years (for example, zero savings and negative net worth), the tool shows a dash and tells you the target is out of reach with current inputs rather than displaying a meaningless number.
Is my financial data private?
Yes. The calculator is 100% client-side — expenses, net worth and savings are processed in your browser and never uploaded.
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