The 4% rule (Bengen rule) states that withdrawing 4% of your portfolio in year 1, then adjusting for inflation, has historically sustained a 30-year retirement in the US. It implies a FIRE number of 25× your annual expenses.

What is Lean FIRE vs Fat FIRE?

Lean FIRE means retiring on minimal expenses (under $40k/yr). Fat FIRE means retiring with a high lifestyle budget ($100k+/yr). The FIRE number scales linearly: if you need $80k/yr, your target is $80k × 25 = $2M.

Is a 4% withdrawal rate safe for 40+ year retirements?

Research suggests 3.3–3.5% may be safer for 40-60 year retirements. Many early retirees use 3.5% (28.6× expenses) to add a safety margin. You can adjust the withdrawal rate in this calculator.

What return rate should I assume for my portfolio?

A diversified 60/40 stock-bond portfolio has historically returned 6–7% real (after inflation). For planning, 5–7% real is a common conservative-to-moderate assumption.

● Financial Independence · Retire Early

FIRE Calculator

Find your FIRE number — the portfolio size that lets you retire and never run out of money.

The FIRE number is 25 times your annual expenses (based on the 4% safe withdrawal rule). If you spend $50,000 per year, you need $1.25 million invested. This calculator shows your target, how far you are, and how long it will take to get there.

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FIRE Calculator

Annual expenses · Current savings · Monthly savings · Expected return

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Your inputs

Annual expenses in retirement

Safe withdrawal rate 4% = classic; 3.5% = conservative

Current invested assets

Monthly savings / investment

Expected real annual return (after inflation)

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Results

Your FIRE number portfolio target

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Already saved

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Still needed

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Progress toward FIRE

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Years to FIRE

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How it's calculated

The FIRE number and time-to-FIRE formula

The FIRE number is derived from the safe withdrawal rate (SWR): the percentage you can withdraw annually without running out of money over a 30–60 year retirement.

FIRE number = Annual expenses ÷ SWR e.g. $50,000 ÷ 4% = $1,250,000 Time to FIRE: solve for n in — FV = Current × (1+r)^n + Monthly × 12 × [(1+r)^n − 1]/r = FIRE number (solved numerically)

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Years at current savings rate
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FIRE: Financial Independence, Retire Early — a movement focused on aggressive saving and investing to retire decades before traditional retirement age.
Safe Withdrawal Rate (SWR): The annual percentage of your portfolio you can spend without depleting it over a long retirement. The 4% rule is the most cited benchmark.
FIRE number: Annual expenses ÷ SWR. At 4% SWR, it's 25× your annual expenses.
Real return: Return after inflation. Using real returns and real expenses means you don't need to model inflation separately.

Disclaimer: the 4% rule is based on US historical data (Bengen 1994). Future returns may differ. Adjust your SWR based on your retirement length, asset allocation, and risk tolerance.

Frequently asked questions

What is the 4% rule?

The 4% rule (Bengen, 1994) states that withdrawing 4% of your portfolio in year 1 — adjusted for inflation each year — has historically sustained a 30-year retirement across various market conditions. It implies a FIRE number of 25× your annual expenses.

Is 4% safe for 40+ year early retirements?

Research (including the Trinity Study) suggests 3.3–3.5% may be safer for 40–60 year retirements. Many early retirees use 3.5% SWR (28.6× expenses) as a conservative buffer. This calculator lets you adjust the rate freely.

What return rate should I use?

Use real (inflation-adjusted) returns. A globally diversified portfolio has historically returned 4–7% real per year. For conservative planning, 5–6% real is widely used. The calculator uses annual compounding on your monthly savings.

What are the FIRE variants?

Lean FIRE: retire on minimal expenses (<$40k/yr). Fat FIRE: retire with a high lifestyle budget ($100k+/yr). Coast FIRE: save enough early that compound interest reaches your FIRE number without further contributions. Barista FIRE: retire partially with some part-time income to cover expenses.