FIRE Number Calculator
The portfolio you need to live off withdrawals, using the 4% rule.
Result
FIRE number
150,000,000
Monthly budget covered
500,000
How it works
Your FIRE number is the capital that lets your withdrawals cover your living costs indefinitely: annual expenses ÷ withdrawal rate. At the classic 4%, that means 25 times your yearly spending — 30,000 a year requires 750,000. The 4% figure comes from the Trinity Study, which tested historical US market data and found that withdrawing 4% of an initial portfolio, adjusted for inflation, survived 30 years in the large majority of cases. Hence the shorthand: multiply annual expenses by 25. Two caveats matter. First, the rule is not a guarantee — it rests on one country's historical returns, a 30-year horizon and a specific stock/bond mix; retiring into a prolonged downturn is its known weak point, which is why many now prefer 3–3.5% for longer retirements. Second, the lever you control best is expenses: cutting annual spending by 5,000 lowers the target by 125,000.
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Frequently asked questions
What is the 4% rule?
A guideline that withdrawing 4% of a portfolio per year is likely to last decades — implying you need 25× expenses.
Is 4% always safe?
It is a rough guide; lower rates (3–3.5%) are safer for very long or early retirements.
Is the 4% rule safe?
It is a historical guideline, not a guarantee. It was derived from past US returns over 30-year windows; longer retirements or a poor sequence of early returns can break it, so many planners now use 3–3.5%.
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