FIRE Calculator Guide: Formula & Worked Example
Short answer
Your Financial Independence number and years to retire early. In the fixed example below, fire number is 1,000,000.00. Your answer depends on the inputs and assumptions you choose.
Formula
FIRE number = yearly expenses ÷ safe withdrawal rate
Use the relationship above with consistent units. The inputs are yearly expenses, current investments, yearly savings, real return (after inflation), safe withdrawal rate. Use the input scale shown beside each field and keep time periods and units consistent. Only round the final result for display.
Worked example
- Yearly expenses
- 40000
- Current investments
- 100000
- Yearly savings
- 30000
- Real return (after inflation)
- 5
- Safe withdrawal rate
- 4
- FIRE number: 1,000,000.00
- Years to FIRE: 17
- Portfolio at FIRE: 1,004,412.82
- Safe yearly income: 40,176.51
Understanding the result
Your Financial Independence number and years to retire early. Start with the base example, then replace each value with the figure that matches your situation.
Yearly expenses
The example uses 40000 for yearly expenses. This is an illustration, not a recommended value. Keep the unit and time period shown by the field.
Current investments
The example uses 100000 for current investments. This is an illustration, not a recommended value. Keep the unit and time period shown by the field.
Yearly savings
The example uses 30000 for yearly savings. This is an illustration, not a recommended value. Keep the unit and time period shown by the field.
Real return (after inflation)
The example uses 5 % for real return (after inflation). This is an illustration, not a recommended value. Keep the unit and time period shown by the field.
Safe withdrawal rate
The example uses 4 % for safe withdrawal rate. This is an illustration, not a recommended value. Keep the unit and time period shown by the field.
What the comparison means
The comparison changes only yearly expenses, keeping every other example input fixed. This isolates that input's effect on the primary result. It does not predict future outcomes.
Rates, fees, eligibility, local tax rules and provider rounding can change the final amount. Reference tax and exchange-rate data may be outdated; verify the official source before deciding.
Comparison
| Scenario | Input | Result |
|---|---|---|
| Lower input | Yearly expenses: 32000 | FIRE number: 800,000.00 |
| Base example | Yearly expenses: 40000 | FIRE number: 1,000,000.00 |
| Higher input | Yearly expenses: 48000 | FIRE number: 1,200,000.00 |
Common mistakes
- Using the wrong units for yearly expenses.
- Comparing results while changing more than one input at a time.
- Rates, fees, eligibility, local tax rules and provider rounding can change the final amount. Reference tax and exchange-rate data may be outdated; verify the official source before deciding.
Checklist
- Confirm yearly expenses.
- Confirm current investments.
- Confirm yearly savings.
- Confirm real return (after inflation) is expressed in %.
- Confirm safe withdrawal rate is expressed in %.
- Check the result against your source or provider.
Calculators Percentage Editorial Team
Calculator guides from the Calculators Percentage team. These introductory examples are educational, not professional advice.
Last reviewed:
Rates, fees, eligibility, local tax rules and provider rounding can change the final amount. Reference tax and exchange-rate data may be outdated; verify the official source before deciding.