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FIRE Calculator (Financial Independence, Retire Early)

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Enter your numbers to see your FIRE projection.

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FIRE Calculator (Financial Independence, Retire Early)

Plug in your income, expenses, current savings and expected real return to see your FIRE number, how many years it will take to reach financial independence, your Coast FIRE point, and a side-by-side sensitivity table that shows how shifting your savings rate moves your retirement age. Everything runs in your browser using a year-by-year compound growth simulation, so the numbers update instantly as you experiment.

使用方法

Enter your current age and your after-tax annual income.
Enter the annual expenses you expect in retirement (in today’s dollars).
Enter your current invested savings.
Set your expected real (after-inflation) annual return — 5% to 7% is a common range for diversified portfolios.
Choose a safe withdrawal rate: 3.5% is conservative, 4% follows the Trinity Study, 4.5% is aggressive.
Review your FIRE number, years to FI, Coast FIRE, Lean / Fat FIRE, and the savings-rate sensitivity grid.

機能

FIRE number – Calculated from your expenses and the safe withdrawal rate you pick (default 25× expenses at 4%).
Years to FI & retirement age – Year-by-year compound simulation, not a closed-form shortcut, so partial years are interpolated.
Coast FIRE number – How much you would need invested today to coast to your full FIRE number by age 65 without contributing another dollar.
Lean / Fat FIRE benchmarks – 15× expenses for a leaner lifestyle, 33× expenses for a fatter cushion.
Savings-rate sensitivity table – Side-by-side comparison from 10% to 80% savings rate, with your own rate highlighted.
Portfolio growth chart – Line chart of projected balance vs. the FIRE target line.
Year-by-year projection – Detailed table of starting balance, contribution, growth, and ending balance per year.

 よくある質問

What is the 4% safe withdrawal rate and where does it come from?

The 4% rule comes from the Trinity Study (1998) and later updates by William Bengen, which back-tested portfolios of US stocks and bonds against historical returns and inflation. The studies found that withdrawing 4% of a starting balance in year one and adjusting that dollar amount for inflation each subsequent year gave most 30-year retirements a very high probability of not running out of money. Critics note that future returns may be lower and that international or longer retirements may warrant a more conservative 3.25% to 3.5% rate.
Why is the FIRE number 25 times annual expenses?

It is the inverse of the 4% safe withdrawal rate: 1 / 0.04 = 25. If you can safely withdraw 4% of a portfolio each year, then a portfolio of 25 times your annual spend should fund those withdrawals indefinitely. Picking a 3.5% rate raises the multiple to about 28.6×, while 4.5% lowers it to about 22.2×.
What is Coast FIRE?

Coast FIRE is the amount you need invested today so that, with no further contributions, compound growth alone will grow your portfolio to your full FIRE number by traditional retirement age (usually 65). Once you hit Coast FIRE, you can stop saving aggressively and simply cover your current expenses while your investments compound in the background.
What is the difference between Lean FIRE and Fat FIRE?

Lean FIRE is financial independence on a modest budget, typically around 15× annual expenses, requiring careful spending in retirement. Fat FIRE is financial independence with a generous lifestyle buffer, often 33× or more annual expenses, allowing for higher discretionary spending and a larger safety margin against bad market sequences.
Should I use nominal or real returns in a FIRE calculation?

Use real returns — that is, returns after subtracting inflation. The 4% rule and the 25× multiple are based on inflation-adjusted spending in today's dollars, so mixing in a nominal return like 10% would dramatically overstate how quickly you reach FI. A common assumption is 5% to 7% real for a diversified equity-heavy portfolio.
Why does the savings rate matter so much more than income?

Years to FI depend on the ratio of what you save to what you spend, not on income alone. Pete Adeney (Mr. Money Mustache) popularized the chart showing that a 50% savings rate gets you to FI in roughly 17 years regardless of absolute income, because higher spending raises your FIRE number proportionally. Boosting your savings rate from 20% to 50% can cut decades off your timeline.