A free, open source FIRE calculator that runs entirely in your browser. No signup, no tracking, no server.
Calculates your numbers for Coast FIRE, Barista FIRE, Fat FIRE, and Lean FIRE — instantly.
- 4 FIRE Types: Coast, Barista, Fat, and Lean FIRE calculations
- Real-time Results: Numbers update as you type
- Zero Dependencies: Single HTML file, no build tools, no frameworks
- Privacy First: Everything runs locally in your browser
- Responsive: Works on desktop, tablet, and mobile
- Download
index.html - Double-click to open in your browser
- That's it.
Or visit coastfirehub.com for the full-featured online version with charts, grid view, and more.
| Type | Description |
|---|---|
| Coast FIRE | Your investments compound to the full FIRE target without further contributions |
| Barista FIRE | Part-time income covers expenses while investments grow |
| Fat FIRE | Enhanced retirement lifestyle at 1.5x-2x standard spending |
| Lean FIRE | Frugal retirement at 75% of standard spending |
FIRE Number = Annual Spending / Safe Withdrawal Rate
Coast FIRE Number = FIRE Number / (1 + Real Return Rate)^Years
Real Return Rate = Investment Return - Inflation Rate
Default assumptions (all adjustable):
- Investment return: 10% (S&P 500 historical average)
- Inflation: 3% (US CPI average)
- Safe withdrawal rate: 4% (Trinity Study)
- Real return: ~7%
- 4% Safe Withdrawal Rate — Trinity Study (Cooley, Hubbard & Walz, 1998)
- Market Returns — S&P 500: ~10% nominal annual returns since 1926
- Inflation Rate — US CPI historical average: ~3% annually
CoastFIRE Hub — Free FIRE calculator toolkit.
MIT License. Use it, share it, modify it.