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FIRE Number Calculator

Enter your annual expenses and expected withdrawal rate to find your FIRE number, then add your savings and contributions to see how many years away you are.

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FIRE number
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Years to FI
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What FIRE means and how the number is calculated

FIRE stands for Financial Independence, Retire Early. The core insight is that once your invested assets are large enough to generate your annual spending through sustainable withdrawals, you no longer need employment income. The magic number is simply your annual expenses divided by your withdrawal rate.

Worked example. Spending $40,000/year in retirement at a 4% withdrawal rate gives a FIRE number of $1,000,000 (equivalently: annual expenses × 25). That’s the portfolio size where you can theoretically live off investment returns indefinitely.

The formula

FIRE number = annual expenses ÷ (withdrawal rate ÷ 100). Years to FI: simulate month by month, applying the monthly return to the current balance then adding your contribution, until the balance reaches the target or 1,200 months pass.

Choosing a withdrawal rate

The lower your withdrawal rate, the safer your retirement but the larger the target. At 3%, the multiplier is 33× expenses; at 4%, it’s 25×; at 5%, it’s 20×. Longer retirements (40+ years) and volatile markets favour a lower rate. Run the calculator with 3.5% and 4% to see the range — the difference can be several years of extra work.

Frequently asked questions

What is the 4% rule and where does it come from?

The 4% rule comes from the 1994 Trinity Study, which analysed historical US stock and bond portfolio data. It found that withdrawing 4% of a portfolio in year one, then adjusting for inflation each year, survived 30 years in the vast majority of historical scenarios. Many FIRE planners use 3–3.5% for longer retirements.

Does the FIRE number account for inflation?

The FIRE number itself is stated in today's money — it assumes your withdrawal rate already provides an inflation-adjusted income. To hit the number in real terms, your investments need to grow faster than inflation over the accumulation period. The calculator uses your expected nominal return; subtract the inflation rate mentally for a conservative estimate.