FIRE Calculator

Written by Great Medico

Updated September 25, 2026 •2 min read

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FIRE Calculator turns the values on the form into a focused planning estimate. It estimates a financial-independence target from annual retirement spending and a withdrawal-rate assumption, then relates that target to current investments, annual saving, and expected return and keeps the arithmetic visible enough to sanity-check.

What this calculator does

FIRE Calculator estimates a financial-independence target from annual retirement spending and a withdrawal-rate assumption, then relates that target to current investments, annual saving, and expected return. The form asks for annual expenses in retirement, safe withdrawal rate, current invested assets, annual savings/investment and expected annual return. The result should therefore be read as a calculation from those displayed assumptions, not as live market, lender, tax, or government-program data unless the page explicitly supplies such a feed.

How to use it

Enter Annual expenses in retirement, Safe withdrawal rate, Current invested assets, Annual savings/investment and Expected annual return. Keep monetary inputs in one currency; the currency selector formats results and does not convert exchange rates. Enter rates and percentages on the scale shown by the field label; do not silently switch between a decimal and a percent. Before calculating, recheck Annual expenses in retirement, Safe withdrawal rate, Current invested assets against the source values you intend to model. If a default value is already filled in, confirm that it matches the scenario you actually want to test rather than assuming the preset is current or personally appropriate.

How the calculation works

A common FIRE target is annual retirement expenses ÷ (safe withdrawal rate ÷ 100). The savings path then grows current investments by the expected return and adds annual savings until the modeled balance reaches that target. This is the calculation method to use when checking the result from FIRE Calculator; values not represented by a visible input should not be inferred as part of the model.

Example

With $50,000 of annual retirement spending and a 4% withdrawal-rate assumption, the classic FIRE target is $1.25 million. Current investments of $100,000 and $25,000 of annual saving can then be grown at the entered expected return to estimate progress toward that target.

How to interpret the result

A lower withdrawal-rate assumption produces a larger target; lower retirement spending produces a smaller one. The years-to-target estimate is very sensitive to investment returns and annual savings. Keep the assumptions with the result so a later recalculation can be compared consistently.

Limitations and notes

A withdrawal rate is a planning assumption, not a guarantee. Taxes, inflation, sequence-of-returns risk, pensions, Social Security, healthcare, changing expenses, asset allocation, and market volatility can materially change the plan. Rounding and timing conventions can cause a real statement or account balance to differ slightly from the model.