FIRE Number Calculator
FIRE stands for financial independence, retire early, and the FIRE number is the size of investment portfolio that could fund your lifestyle indefinitely from withdrawals alone. This calculator finds that target with one clean relationship: divide your planned annual expenses by a safe withdrawal rate, the percentage of the portfolio you draw each year. A four percent rate, drawn from long-run studies of sustainable retirement spending, is the most cited starting point and is equivalent to saving 25 times your yearly costs. Lower the rate for a more conservative cushion against poor early returns, or raise it if you expect other income such as a pension or Social Security to share the load. Enter your expected annual spending and the withdrawal rate you are comfortable with, and the tool returns both the FIRE number and the implied savings multiple. The result is a planning target, not a guarantee: real markets vary, inflation erodes spending power, and a run of poor early returns matters, so most people build in a safety margin and keep some flexibility in their spending. Every figure is computed deterministically from the formula shown below, with a worked example that reconciles exactly to the calculator defaults.
The FIRE number divides spending by the withdrawal rate: FIRE number = annual expenses / withdrawal rate. With 40,000 of annual expenses and a 4% rate, the target portfolio is $1,000,000.00, which is 25 times yearly spending.
FIRE number formula
FIRE number = annual expenses / w
w = safe withdrawal rate (as a decimal)
Savings multiple = 1 / w
(a 4% rate equals 25 times expenses)
Dividing by the withdrawal rate is the same as multiplying by its reciprocal, so a 4 percent rate gives a target of 25 times annual expenses, while a 3 percent rate gives about 33 times.
Worked example
Suppose your planned annual expenses are 40,000 dollars and you use a 4 percent safe withdrawal rate.
- Convert the rate: 4% = 0.04
- FIRE number: 40,000 / 0.04 = 1,000,000.00
- Savings multiple: 1 / 0.04 = 25.00 (25 times expenses)
The FIRE number is 1,000,000.00 dollars, equal to 25 times annual spending. These are the calculator's default inputs, so the result matches the widget exactly.
FIRE Number Calculator: frequently asked questions
What is a safe withdrawal rate?
A safe withdrawal rate is the percentage of a portfolio you can draw each year with a high chance of the money lasting through retirement. The four percent figure comes from studies of historical market returns over long horizons. It is a guideline, not a guarantee, and many early retirees use a lower rate for extra safety.
Why does the 4% rate equal 25 times expenses?
Dividing by four percent is the same as multiplying by 25, because one divided by 0.04 is 25. So a four percent rule and a 25-times-expenses rule are two ways of stating the same target. A three percent rate corresponds to roughly 33 times expenses.
Should I lower the rate for early retirement?
Many people retiring early use a more conservative rate, such as three to three and a half percent, because their portfolio must last far longer than a traditional retirement and faces more sequence-of-returns risk. A lower rate raises the FIRE number but adds a safety margin.
Does this account for Social Security or a pension?
Not directly. If you expect Social Security or a pension to cover part of your spending, you can subtract that income from your annual expenses before entering the figure, which lowers the portfolio you need to fund yourself. The Social Security Administration publishes benefit estimates to help.
Is the FIRE number a guarantee?
No. It is a planning target based on a steady withdrawal assumption. Real returns vary, inflation erodes spending power, and a run of poor early returns can strain a portfolio. Most people pair the target with flexible spending, a cash buffer, or a part-time income to manage that risk.
Official sources
- Retirement income and benefits guidance: US Social Security Administration (SSA). As at 25 June 2026.
Reviewed by the CalculatorHub team, edited by James Graham, 25 June 2026. See our methodology. This is general information, not financial, tax, legal or investment advice.