Coast FIRE means you've saved enough that compound growth alone will reach your FIRE number by your target retirement age — so you can stop aggressively saving and just coast.

At 35, I hit my coast FIRE number: approximately $280,000 in investments. With 30 years of compounding at an assumed 7% real return, that grows to roughly $2.1 million by age 65 — enough to sustain about $84,000/year on the 4% rule.

What this means in practice: I no longer invest aggressively. I cover my expenses with my income, enjoy some lifestyle improvements I'd deferred, and contribute to my 401k up to the match. My net worth is still growing, just not at the aggressive pace it was.

The mental benefit has been enormous. The financial anxiety that had driven every decision for 12 years essentially evaporated. I still work because I choose to, not because I must.