FIRE calculator
This divides annual spending by a withdrawal rate you choose, then counts years of saving toward that balance. A coast figure is the amount today that grows to the target with nothing added. A 4% rate is a common illustration, not a promise that the rate will last. The FIRE guide uses the same example.
FI number = annual spending the portfolio must replace ÷ withdrawal rate. Today's-dollar mode uses the real return (1 + nominal) ÷ (1 + inflation) − 1. Nominal mode can grow that target with inflation each year. Coast number = FI number ÷ (1 + real return)years until that date
FI number
Enter spending, a withdrawal rate, the portfolio, annual savings, a return, and coast years.
Keep these numbers
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How to estimate a FIRE number
- Enter annual spending and a withdrawal rate. 4 means a 4% withdrawal. Optional tax grosses the spending up, because the portfolio has to fund the tax as well as the spending. Optional part-time income is used only for a separate, smaller number.
- Choose today's dollars or nominal dollars. Today's dollars use a real return. Nominal dollars keep a fixed-dollar target unless you enter inflation, which then grows that target each year. Savings stay in the same basis as the mode you picked.
- Enter the portfolio, annual savings, and return. Each year the balance grows at the rate for that mode, then the annual savings is added, until the balance reaches the target or 80 years pass.
- Read the coast balance. Coast years are how long the balance would compound with nothing added. The coast figure is always an amount you would need today. A lower real return or a shorter wait raises it.
Frequently asked questions
- How do you calculate a FIRE number?
- Divide the annual spending the portfolio must replace by the withdrawal rate you type. Spending of $40,000 at a 4% withdrawal rate is a $1,000,000 FI number, because 1 ÷ 0.04 = 25. A 4% rate is a common illustration from historical studies of about 30-year retirements. A longer retirement can need a lower rate. This calculator does not estimate the odds that a rate will last.
- What is the coast number?
- It is the balance today that grows to the FI number with no further contributions, at the real return implied by the nominal return and inflation you type. At 7% nominal with no inflation for 20 years, a $1,000,000 FI number implies a coast balance near $258,419. If your portfolio is already there, later contributions are optional under those assumptions.
- What is the difference between today's dollars and nominal dollars?
- Today's-dollar mode keeps spending, savings, and the FI number in current purchasing power and compounds at the real return (1 + nominal) ÷ (1 + inflation) − 1. Nominal mode treats the spending figure as a future dollar amount; if you enter inflation, that target grows each year while savings stay a constant nominal amount. A fixed $1 million future target with a 7% nominal return is not the same as keeping today's $40,000 of spending power.
- Is this investment advice?
- No. The calculator is for general informational and educational purposes only. Spending, return, tax, and withdrawal rate are assumptions you type. They are not a retirement plan.
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