Coast FIRE is the amount that, left alone, grows to your retirement goal without another dollar added. See your coast number and whether you have hit it.
Your numbers
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Coast FIRE number
Needed today to coast
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The FIRE number is your spending divided by the withdrawal rate; the coast number discounts it back to today at your real (after-inflation) return. Reaching it means you can stop contributing and still retire on schedule, though most people keep saving for a cushion. Real returns are not guaranteed.