FIRE Calculator — Calculate Your Financial Independence Number & Retirement Date

A FIRE calculator computes your Financial Independence, Retire Early number — the portfolio size at which you can stop working and live off investment returns indefinitely. Enter your annual expenses, current savings, monthly contribution, and expected investment return to see your FIRE number and how many years until you reach it. The FIRE movement is built on one core insight: financial independence is about your savings rate and spending level, not your income.

How to use this FIRE Calculator

1. 1Enter your annual living expenses — the amount you spend per year in retirement. Be realistic; underestimating expenses is the most common FIRE planning mistake.
2. 2Enter your current invested net worth (savings + brokerage + retirement accounts, excluding home equity).
3. 3Enter your monthly savings and investment contribution.
4. 4Enter your expected annual investment return. Most FIRE planners use 7% (inflation-adjusted S&P 500 historical average).
5. 5The calculator shows your FIRE number (25× expenses at 4% SWR), current savings rate, and years to financial independence.

How to calculate your FIRE number

Your FIRE number is the portfolio size that generates enough annual returns to cover your expenses indefinitely using the 4% safe withdrawal rate, derived from the Trinity Study. At 4% withdrawal, a diversified portfolio has historically sustained 30+ year retirements across all historical market periods.

Financial independence calculator example: $50,000 annual expenses, $150,000 saved

1. 01Annual expenses: $50,000. FIRE number: $50,000 × 25 = $1,250,000.
2. 02Current savings: $150,000. Monthly contribution: $2,500 ($30,000/year). Annual return: 7%.
3. 03Savings rate: If income is $80,000 and expenses are $50,000, savings rate = ($80,000 − $50,000) ÷ $80,000 = 37.5%.
4. 04Future value calculation: growing $150,000 at 7% plus $30,000/year contributions.
5. 05Result: approximately 18 years to reach $1,250,000.

What affects your FIRE number and timeline?

Tips and things to know

• ✓Reducing spending has a double impact: it lowers your FIRE number AND increases your savings rate — a $10,000 annual spending cut gets you to FIRE years faster through both effects simultaneously.
• ✓The 4% rule was designed for 30-year retirements. If you plan to retire at 40, consider using a 3.5% withdrawal rate, making your FIRE number 28.5× annual expenses.
• ✓Tax-advantaged accounts (401k, Roth IRA, HSA) are critical for FIRE — the Roth conversion ladder and 72(t) SEPP rules allow penalty-free access before age 59½.
• ✓Sequence-of-returns risk is the biggest FIRE threat: retiring into a bear market can deplete a portfolio faster than the historical simulations suggest. Keep 1–2 years of expenses in cash.
• ✓Geo-arbitrage — moving to a lower cost-of-living area or country after reaching FIRE — can dramatically extend portfolio longevity or allow retiring with a smaller nest egg.

FIRE Calculator — bottom line

The FIRE movement is built on two numbers: your target portfolio size (typically 25× annual expenses) and your savings rate. The higher your savings rate, the faster you reach the target, and the math is non-linear. At a 10% savings rate, it takes approximately 43 years to reach FIRE. At a 25% savings rate, about 32 years. At a 50% savings rate, roughly 17 years. At 70%, approximately 8.5 years. Small increases in savings rate produce large reductions in working years. The most common FIRE planning mistake is using the 4% withdrawal rate as a universal rule. The 4% rule was derived from a specific 30-year retirement window using 20th-century US market data. For early retirees with 40–60-year retirements, many researchers suggest 3–3.5% is more conservative. A $1.5M portfolio at 3.5% generates $52,500 per year; at 4% it generates $60,000. That gap is significant if you retire at 40 with a 45-year horizon. Second common mistake: projecting without accounting for taxes. Most FIRE calculators model pre-tax growth on pre-tax savings. In reality, the account type matters: a portfolio of $1.5M in a traditional 401(k) has a tax liability embedded in it; a Roth IRA does not. Plan your FIRE number with after-tax portfolio value. Third: ignoring healthcare costs before Medicare eligibility at 65. Health insurance on the open market for early retirees is a significant expense — factor $500–$1,500/month per person into your annual FIRE budget before declaring your number final.

Official resources and further reading