FIRE Number Calculator
Work out the investment portfolio you'd need to cover your annual expenses under the FIRE 'safe withdrawal rate' rule.
- Equivalent monthly budget
- $5,000
This calculator provides estimates only. It is general information, not financial or taxation advice, and doesn't account for your full personal circumstances. Confirm figures with your lender or a licensed adviser before making a decision.
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How this calculator works
Your "FIRE number" (Financial Independence, Retire Early) is the size investment portfolio that could theoretically fund your living expenses indefinitely, by withdrawing a fixed percentage each year and letting the rest keep growing. It's calculated simply as annual expenses divided by your chosen withdrawal rate — commonly 4%, based on historical research into how often a portfolio survives 30 years of withdrawals without running out.
Enter your annual living expenses and the withdrawal rate you're comfortable with (lower rates are more conservative and require a bigger portfolio; higher rates need less saved but carry more risk of running out).
Worked example: $60,000 a year in expenses at a 4% withdrawal rate gives a FIRE number of $1,500,000 ($60,000 ÷ 0.04). Drop the withdrawal rate to a more conservative 3.5% and the required portfolio rises to about $1,714,286 for the same expenses.
The 4% rule comes from research on historical US market returns over rolling 30-year periods — it doesn't guarantee success, especially for retirements longer than 30 years, in different markets, or during poor early-retirement sequences of returns. Many people use a lower rate (3–3.5%) for extra safety margin, particularly for an early retirement that could span 40+ years.
Frequently asked questions
- Why 4%? Where does that number come from?
- It's based on the 'Trinity study' and similar research testing how often a diversified portfolio survived 30 years of inflation-adjusted withdrawals using historical US market returns — 4% held up in the vast majority of historical periods tested, though it's not a guarantee.
- Should I use a lower withdrawal rate for early retirement?
- Many people retiring earlier than the traditional age (with a much longer time horizon than 30 years) choose a more conservative rate like 3–3.5% for extra safety margin, since the original research was based on a 30-year retirement window.
- Does this account for the age pension or other income?
- No — this is a standalone calculation based purely on your expenses and portfolio. Other income streams (the age pension, part-time work, rental income) would reduce how much your portfolio needs to cover on its own.