Free calculator · Personal Finance
FIRE Number
Calculates a FIRE number, the portfolio that supports a level of annual spending at a chosen withdrawal rate, and estimates the years until the current portfolio and savings pace could reach it. Inputs are annual spending, the withdrawal rate, the current portfolio, savings per year, and an assumed annual return.
By Devon Coombs, CPA, MBA · Teaching Professor of Finance, Santa Clara University · Reviewed August 2026
Interactive Tool
FIRE Number
FIRE number
$1,500,000
$60,000 ÷ 4.0% withdrawal rate
Years to reach it
20
saving $30,000/yr at 5.0%
Progress today
13%
$200,000 of $1,500,000
FIRE = $60,000 ÷ 0.040 = $1,500,000; portfolio grows at 5.0%/yr plus $30,000 saved each year
The 4% guideline comes from historical US market studies; a lower withdrawal rate trades a larger target for more margin against poor early returns. Spending here is in today's dollars, so pair it with a REAL return assumption (roughly the nominal return minus inflation, often 4% to 5% for a stock-heavy mix) rather than a nominal one.
Learn the concept
This calculator comes from the free Corporate Finance: The 10 Laws of Finance course, where the concept is taught with readings, worked examples, and practice questions.
Precomputed reference tables
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Built by Devon Coombs, CPA, MBA, Teaching Professor of Finance at Santa Clara University.