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FIRE Calculator: Years to Financial Independence

Enter what you spend in a year, what you have invested and what you add each month. The calculator finds your FI number and projects how long it takes to reach it.

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Years to financial independence

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FI number
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Progress toward target
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Monthly income at that point
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Tips for using the fire calculator

  • Lowering spending helps twice: it shrinks the target and frees money to invest.
  • The 4% rule comes from US historical data over 30-year retirements. For a 40 to 50 year retirement, many planners use 3.25% to 3.5%.
  • Include health insurance, taxes on withdrawals and irregular costs such as car replacement in your annual spending.

How the fire calculator works

FIRE (financial independence, retire early) rests on one idea: once your investments can fund your spending indefinitely, work becomes optional. The target, often called your FI number, comes from the withdrawal rate you are comfortable with.

FI number = Annual spending ÷ Withdrawal rate
Balance next month = Balance × (1 + annual return ÷ 12) + Monthly contribution

At a 4% withdrawal rate the FI number is 25 times your annual spending. The calculator then grows your current balance month by month, adding your contribution, until it reaches the target. Use a real return (after inflation) so that the FI number stays in today's dollars; 4% to 6% is a common planning range for a stock-heavy portfolio.

Worked example

You spend $48,000 a year, have $60,000 invested, add $1,500 a month and assume a 5% real return. At a 4% withdrawal rate your FI number is 48,000 ÷ 0.04 = $1,200,000. Compounding monthly, the balance reaches that in about 26 years. Cut spending to $40,000 and the target falls to $1,000,000, which also shortens the timeline to about 23.6 years because the same savings cover a smaller goal.

Frequently asked questions

What is a FIRE number?

It is the invested balance at which a chosen withdrawal rate covers your yearly spending. At 4% it equals 25 times annual spending; at 3.5% it is about 28.6 times.

Is the 4% rule safe?

The rule comes from the Trinity study and William Bengen's research, which found a 4% inflation-adjusted withdrawal survived most 30-year US periods. It is a guideline, not a guarantee, and longer retirements call for a lower rate.

Should I use a nominal or real return?

Use a real return, meaning the expected return minus inflation. That keeps the FI number and the timeline in today's dollars, so you do not need to inflate your spending separately.

Does this include Social Security or pensions?

No. If you expect other income later, subtract it from your annual spending to see a smaller target, keeping in mind it may not start until your 60s.

Updated October 2026. Results are estimates for education, not financial or medical advice. All math runs in your browser; nothing you type is sent anywhere.

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