FIRE calculator

Your FI number (or fire number) is the portfolio size that could support annual spending at your chosen safe withdrawal rate (SWR). A common educational shortcut is the 25× rule: multiply annual expenses by 25 when using a 4% withdrawal rate.

Formula: FI number = annual spending need ÷ (withdrawal rate ÷ 100). If you expect to spend less in retirement, use the post-FIRE spending percentage in Advanced. Subtract a pension or Social Security estimate with the passive income offset field.

Use FI number mode for a quick target, or Reach FIRE to see how long saving might take at your current rate.

A higher savings rate usually shortens the path to early retirement because you spend less and invest more each year. With after-tax income: savings rate = annual savings ÷ annual income.

There is no single “correct” rate—housing costs, debt, and family size all matter. Many FIRE plans sit between roughly 20% (slower) and 50%+ (aggressive). Tap the 60% savings rate preset above to stress-test a high-savings timeline (~12.25 years in our bundled example at 5% return).

To split take-home pay into needs, wants, and savings first, try our 50/30/20 rule calculator or CFPB budgeting tools, then enter a realistic savings figure here.

The 4% rule is a safe withdrawal rate (SWR) shortcut from retirement research (often discussed alongside Trinity-study follow-on work). It is not a guarantee for every portfolio, market, or retirement length.

Conservative planners often try 3.5% for longer retirements. Others model 4.5% when timelines are shorter—usually with flexible spending in real life.

Change the withdrawal rate in the calculator to see how your FI number shifts. For doubling-time intuition without withdrawal math, see our Rule of 72 calculator.

Lean FIRE, regular FIRE, and Fat FIRE describe different spending targets—not separate calculators. The results panel applies illustrative multipliers to your spending need before applying your withdrawal rate.

Barista FIRE (part-time work covering part of expenses) is a useful label, but this calculator does not model part-time wages—adjust spending or savings manually for that scenario.

Coast FIRE is the portfolio you need today so that, with no further contributions, investments could grow to your full FI number by a traditional retirement age (often 65).

In Coast FIRE mode, compare your current balance to the coast target. If you are already at or above coast, you could stop new contributions toward the full FI number while still working for cash flow—or keep saving to reach full FIRE sooner.

You do not need a separate coast fire calculator page: switch to Coast mode above to see your coast number alongside the same income and spending inputs.

We use a monthly simulation (same convention as our 401(k) tools): each month the portfolio grows at your assumed return, then your annual savings are added in equal monthly deposits until the balance reaches your FI number or age 100.

There is no Monte Carlo simulation, tax bracket logic, or asset-allocation matrix here. For generic growth without an FI stop rule, use our compound interest calculator.

FIRE age is when this model says your portfolio first hits your FI number with your savings and return assumptions. Traditional retirement age (often 65) still matters for Medicare eligibility, pension start dates, and Coast FIRE math—even if you plan to leave full-time work earlier.

Reaching FIRE on paper does not automatically cover healthcare before Medicare, one-time costs, or sequence-of-returns risk. Treat the FIRE age hero as a planning milestone, not a promise you can withdraw safely every year without adjusting spending.

This FIRE calculator stops when your balance hits a spending-based FI number and shows withdrawal-based income. A compound-growth tool keeps projecting without that retirement-spending target—better when you only need “how much will this grow?”

Include 401(k), 403(b), IRA, and taxable balances in current portfolio. Employer match and IRS deferral limits change how fast accounts grow—model those details in our 401(k) calculator or 403(b) calculator, then roll the projected balance into this view.

Selling investments for living expenses is a tax question, not a FIRE timeline question—use our capital gains tax calculator when you need sale tax estimates.

This tool does not enforce contribution caps or match formulas; it treats your portfolio and savings inputs as given.

FIRE math starts with reliable after-tax income and honest annual spending. If you only know gross salary, convert with our paycheck calculator or annual income calculator, then enter savings as income minus expenses—or enter expenses directly in the calculator.

The 50/30/20 rule is a simple check that your savings bucket is large enough to support aggressive FIRE targets. It is a guideline, not a FIRE requirement—high-cost cities often need custom splits.

Nominal return and withdrawal math can overstate future purchasing power. Turn on inflation in Advanced to see optional context, or stress-test purchasing power in our inflation calculator.

Post-FIRE spending can differ from today—use the post-FIRE spending percentage in Advanced if you expect lower or higher costs in retirement.

High-interest debt often belongs ahead of aggressive investing in a real plan—the guaranteed “return” from paying off a 20% APR card usually beats uncertain market averages in the short run.

This calculator does not schedule debts or model minimum payments. Use our debt payoff calculator for avalanche vs snowball timelines, then enter a realistic savings rate here once cash flow frees up.