Coast FIRE number at 40
Coast FIRE means you've invested enough that, even if you never save another dollar, compound growth alone carries you to a full retirement. At age 40, roughly $369,000 invested today would grow to a $1,250,000 nest egg by 65 (assuming a 5% real return) — enough to fund a comfortable retirement. After that, your paycheck only has to cover today's expenses.
Your Coast FIRE number at 40, by return assumption
Coast FIRE is sensitive to the return you assume over the 25 years to 65 — a higher real return means a smaller amount needs to compound:
| Return | Coast number | Growth |
|---|---|---|
| 4% real | $469,000 | 2.7× |
| 5% real | $369,000 | 3.4× |
| 6% real | $291,000 | 4.3× |
What Coast FIRE does and doesn't mean
Hitting your Coast FIRE number is a genuine milestone: your retirement is essentially on autopilot, and you gain the freedom to take a lower-paying but more fulfilling job, go part-time, or stop retirement contributions and spend that money now. It does not mean you can stop working — you still need income to cover current living expenses until you actually retire.
The number rests on two assumptions worth pressure-testing: the return you earn over the years to 65 (markets are uncertain, and a weak stretch early does outsized damage), and the target nest egg itself, which depends on your future spending. Model your own inputs to see how sensitive your coast number is to both.
A shorter coast leaves less room to be wrong
Coasting at 40 rests on the same idea as at 25, but the margin is thinner. With roughly 25 years of compounding left rather than 40, the required balance is considerably larger, and there is far less time for a weak stretch of returns to recover before you actually need the money.
The compressed runway also brings you closer to sequence-of-returns risk, which peaks in the first decade of retirement. A shorter coast gives a disappointing overall return less time to bounce back, and the handoff from coasting to drawing down arrives soon — so a bad market around that transition can do lasting damage, exactly when you have the least room to wait it out.
The response is verification, not alarm. Recompute the coast number against a deliberately conservative real return; if it still reaches the target you have genuine cushion, and if it only clears the bar at an optimistic rate, a few more years of saving now buys margin that is hard to recover later. A cash buffer near the transition also lets you avoid selling into a downturn.
Common questions
What is the Coast FIRE number at 40?
About $369,000 invested at age 40, assuming a 5% real return, would grow to a $1,250,000 retirement nest egg by 65 with no further contributions. At a 6% real return it's closer to $291,000; at 4%, about $469,000.
Does Coast FIRE mean I can stop working?
No — it means you can stop saving for retirement. You still need enough income to cover your current living expenses until you retire; your retirement savings just grow on their own from here.
What return should I assume for Coast FIRE?
A real (after-inflation) return of about 5% is a common, moderate assumption for a stock-heavy portfolio over a long horizon. Because markets are uncertain, it's wise to check your number against a lower rate too.