Your Coast FIRE number is the portfolio balance that — with zero additional contributions — compounds into full financial independence by your target retirement age. Hit it, and every dollar you earn after that is yours to spend. All math runs privately in your browser.
Coast FIRE means you've saved enough, early enough, that compound growth alone will carry your portfolio to your full retirement number. You still work to cover current expenses — but you never have to save for retirement again. It's the most achievable milestone in the FIRE movement, and for most people it arrives a decade or more before full financial independence.
We take your full FIRE number (annual spending ÷ safe withdrawal rate), then discount it back to today using your inflation-adjusted return: Coast Number = FIRE Number ÷ (1 + real return)years until retirement. The chart shows the "coast curve" — the balance you need at every age — against your projected portfolio. Where the lines cross is your coast date.
Assuming retirement at 65, 7% returns, 2.5% inflation, and a 4% withdrawal rate:
| Coast at age | $40k/yr spending | $50k/yr | $60k/yr | $80k/yr |
|---|---|---|---|---|
| 25 | $179,000 | $224,000 | $269,000 | $359,000 |
| 30 | $222,000 | $278,000 | $333,000 | $445,000 |
| 35 | $276,000 | $345,000 | $413,000 | $551,000 |
| 40 | $342,000 | $427,000 | $512,000 | $683,000 |
| 45 | $424,000 | $529,000 | $635,000 | $847,000 |
| 50 | $525,000 | $656,000 | $787,000 | $1,050,000 |
Want the full picture — Monte Carlo stress tests, budget auditing, and the Financial Order of Operations? Use the complete FIREplanner.AI dashboard.