How to Calculate FIRE
What is FIRE?
The FIRE (Financial Independence, Retire Early) calculator computes your FIRE number — the total nest egg you need to retire early and live indefinitely on investment returns. Based on the 4% rule, you need 25× your annual expenses saved.
Formula
Step-by-Step Guide
- 1Calculate annual expenses: everything you spend per year in retirement
- 2FIRE number = Annual expenses × 25 (using the 4% safe withdrawal rate)
- 3The 4% rule is derived from the Trinity Study showing a diversified portfolio survives 30+ years at 4% withdrawal
- 4Lean FIRE: frugal lifestyle, smaller number | Fat FIRE: comfortable lifestyle, larger number
Worked Examples
Frequently Asked Questions
What is Fire Calc?
The FIRE (Financial Independence, Retire Early) calculator computes your FIRE number — the total nest egg you need to retire early and live indefinitely on investment returns. Based on the 4% rule, you need 25× your annual expenses saved
How accurate is the Fire Calc calculator?
The calculator uses the standard published formula for fire calc. Results are accurate to the precision of the inputs you provide. For financial, medical, or legal decisions, always verify with a qualified professional.
What units does the Fire Calc calculator use?
This calculator works with inches, percentages. You can enter values in the units shown — the calculator handles all conversions internally.
What formula does the Fire Calc calculator use?
The core formula is: FIRE number = Annual expenses × 25 (using the 4% safe withdrawal rate). Each step in the calculation is shown so you can verify the result manually.
Ready to calculate? Try the free FIRE Calculator
Try it yourself →