FIRE Number Calculator (Financial Independence)
Calculate the portfolio size needed for financial independence using the 4% safe withdrawal rate.
What this calculates
FIRE (Financial Independence, Retire Early) sets a target portfolio size where investment returns cover annual expenses indefinitely. The classic rule of thumb is 25× annual expenses, derived from the 4% safe withdrawal rate from the Trinity study. Adjust for shorter/longer horizons and risk tolerance.
Formula & how it works
FIRE number = annual expenses ÷ SWR. Default SWR = 4% → 25× expenses. Conservative 3% → 33×. Coast FIRE = FIRE ÷ (1 + r)^(years to retirement).
Worked example
Annual expenses $48,000. At 4% SWR: $48,000 ÷ 0.04 = $1,200,000. At 3.5% SWR: $1,371,000.
Frequently asked questions
Is the 4% rule safe?
Based on US data 1926-1995 for 30-year retirements. For 50+ year horizons, many planners drop to 3.25-3.5%.
Lean FIRE / Fat FIRE?
Lean FIRE = expenses ~$25-40k (minimal lifestyle). Fat FIRE = $100k+ (luxury). Same math, different inputs.
Coast FIRE?
Stop contributing now and let compounding reach FIRE by traditional retirement. Calculate by discounting FIRE number back to today.
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