Browse Code
A free, open-source FIRE (Financial Independence, Retire Early) calculator that runs in a single HTML file with zero dependencies.
Calculates your numbers for Coast FIRE, Barista FIRE, Fat FIRE, and Lean FIRE — instantly in your browser.
The math:
- FIRE Number = Annual Spending / 4% (Trinity Study safe withdrawal rate)
- Coast FIRE Number = FIRE Number / (1 + Real Return Rate)^Years
Default assumptions (all adjustable):
- Investment return: 10% (S&P 500 historical average)
- Inflation: 3%
- Safe withdrawal rate: 4%
- Real return: ~7%
No signup. No tracking. No server. Download the HTML file and run it offline.
Also available as a full web app at coastfirehub.com with interactive charts, Coast FIRE Grid, and a Chrome extension.
Features
- Coast FIRE calculator — calculates how much to invest today
- Barista FIRE calculator — part-time income + investments
- Fat FIRE / Lean FIRE — different lifestyle spending levels
- Coast FIRE Grid — lookup table by age
- Real-time results — updates as you type
- Zero dependencies — single HTML file, runs offline
- Open source — MIT license
- No account required — runs in browser, no data collection
Project Samples
