FIRE number calculator
Turn your annual spending into the portfolio size that could sustain it indefinitely, using the 4% rule and safer variants.
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FIRE number
What it measures
Calculates the portfolio size needed to retire and live off investment income indefinitely (FIRE stands for financial independence, retire early). It is based on the 4% rule.
When to use it
Use it for long-term financial planning. It gives you a specific target to aim for.
Watch out for
The 4% rule assumes a 30-year retirement. For longer retirements, such as retiring at 40, many planners suggest a more conservative withdrawal rate of 3–3.5%.
FIRE number
The portfolio size needed to retire.
How it works
FIRE Number = Annual Spending / Safe Withdrawal Rate (at 4%: Spending × 25)The logic comes from the Trinity study: historically, a diversified portfolio survived 30-year retirements when withdrawals started at 4% of the balance and grew with inflation. Invert that and your target portfolio is simply annual spending times 25. The withdrawal rate is the whole game: it embeds assumptions about market returns, inflation, and how long the money must last. Early retirees with 40-50 year horizons often plan on 3-3.5%, which pushes the multiple from 25× toward 29-33×.
Worked example
Spending €40,000 a year means a €1,000,000 portfolio at the 4% rule. Prefer the safer 3.5% for a longer retirement? The target rises to about €1,143,000. Cutting spending by €500 a month does double duty: it lowers the target by €150,000 and frees cash to invest. That is usually a far faster path to the number than chasing higher returns.
Common questions
What is a FIRE number?
It is the portfolio size at which investment returns can sustainably fund your lifestyle (FIRE stands for Financial Independence, Retire Early). At a 4% withdrawal rate, it equals 25 times your annual spending; the calculator lets you test other rates.
Is the 4% rule still safe?
It survived every historical 30-year period in the original US studies, but it assumes that history rhymes. For retirements longer than 30 years, or expensive markets, many planners model 3-3.5% instead. Flexibility (spending less in bad years) buys a lot of extra safety.
Does the FIRE number include my home?
Only assets that produce returns count: index funds, rental income, bonds. Your primary residence lowers your spending (no rent) rather than funding withdrawals, so it enters the calculation through the spending side, not the portfolio side.
Last reviewed July 2026