RETIREMENT · FIRE

FIRE Calculator

Calculate your Financial Independence (FI) number, savings rate, and years to FIRE. Based on the 4% safe withdrawal rule and your current portfolio trajectory.

LAST REVIEWED · APR 08, 2026 · BY A. CHEN, CFP®
You need
$1,000,000
FIRE InputsReset
Annual spending
$40,000
$10K$200K
Annual incomeAfter tax
$80,000
$10K$500K
Current portfolio
$100,000
$0$3M
Expected return
7%
1%12%
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How the FIRE calculator works

FIRE (Financial Independence, Retire Early) starts with one number: 25 times your annual spending. That’s how much you need invested to safely withdraw 4% per year indefinitely, based on the Trinity Study. Your savings rate determines how quickly you get there.

The savings rate is everything

At a 50% savings rate with 7% returns, you reach FI in roughly 17 years regardless of income level. At 75%, it’s about 7 years. The math is counterintuitive: saving more both increases your portfolio growth and decreases your FI target (because you’re proving you can live on less).

After FIRE

Reaching your FI number doesn’t mean you must stop working. Most FIRE adherents continue earning in some capacity — they just have the freedom to choose work they enjoy rather than work they need.

Methodology. FI Number = Annual Spending × 25 (based on the 4% safe withdrawal rule). Savings Rate = (Income − Spending) / Income × 100. Years to FI calculated iteratively: each year, portfolio grows by return rate plus annual savings, until it reaches the FI number.

Sources

  • Trinity Study (Cooley, Hubbard, Walz, 1998) — 4% safe withdrawal rate
  • Historical S&P 500 returns (DQYDJ)
  • Mr. Money Mustache — ‘The Shockingly Simple Math Behind Early Retirement’
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RELATED RETIREMENT CALCULATORS
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Safe Withdrawal Rate Calculator ↗
Determine a sustainable withdrawal rate for your retirement portfolio. See your annual and monthly income along with a historical success probability based on the Trinity Study framework.
Compound Interest Calculator ↗
Calculate how your money grows with compound interest. Choose monthly, quarterly, or annual compounding and add regular contributions to see the power of compounding over time.

Frequently asked questions

Is the 4% rule still valid? +
The original Trinity Study found 4% succeeded in 95% of 30-year periods. Recent research suggests 3.3–3.5% may be more appropriate given current valuations and lower expected returns. The calculator uses your chosen rate.
What if I return -1 for years to FI? +
That means your spending exceeds your income, so you’re not saving anything. You’ll need to either earn more or spend less before FIRE math works.
Does this account for taxes and healthcare? +
Only indirectly — include taxes and health insurance premiums in your annual spending figure. After FIRE, these often change significantly, so model them explicitly.
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