What is Coast FIRE?
Coast FIRE is the point at which your existing investments will grow large enough through compound interest to support your retirement, even if you stop contributing today. You still need income to cover living expenses, but you no longer need to save more for retirement.
How the calculator works
Enter your current age, portfolio value, expected real return, retirement age, and target annual spending. Coast FIRE Calculator outputs:
- Your Coast FIRE number (the amount needed today to coast)
- The age you will reach Coast FIRE at your current savings rate
- Year-by-year portfolio projection
- Comparisons to Lean FIRE, Fat FIRE, and Barista FIRE
Why use it
Most retirement calculators ask "how much should I save per month?" Coast FIRE flips the question: "how much do I need invested before I can stop the savings treadmill?" For people in their 30s and 40s, the answer is often closer than they think.
The tool is free, requires no signup, and runs entirely in your browser - your numbers stay private.
Common pitfalls
- Underestimating inflation - use real returns
- Ignoring sequence-of-returns risk - build a buffer
- Not revisiting assumptions - recalculate yearly
Why I built it
Every existing Coast FIRE spreadsheet I tried had hidden bugs - wrong inflation handling, missing sequence-of-returns risk, or assumptions buried in cells. Coast FIRE Calculator is open in the browser, transparent in its math, and requires no spreadsheet skills. Try it at coastfirecalculator.io.
