·6 min read
Coast FIRE explained
Why “coasting” is about stopping aggressive saving — not retiring tomorrow.
Coast FIRE answers a different question than classic FIRE. Instead of “Can I quit forever today?”, it asks: “Do I already have enough invested that compound growth can reach my full FIRE number by a traditional retirement age — even if I never invest another dollar?”
The discount formula
If full FIRE is T, real return is r, and years until traditional retirement is n, then coast number ≈ T ÷ (1+r)^n. The longer the runway and the higher the assumed return, the smaller the nest egg you need today.
What Coast FIRE is not
- Not permission to ignore healthcare or emergency funds.
- Not a guarantee markets will deliver a constant real return.
- Not early retirement — many “coasters” still work for lifestyle, purpose, or benefits.
Use the Coast FIRE calculator at /calculators/coast-fire to compare shortfall vs surplus under conservative returns. When in doubt, lower r and extend your horizon.