There's a point in the wealth-building journey where something shifts. Your portfolio is large enough that — even if you never add another dollar to it — compound growth alone will carry it to full retirement size by a target date. That point is called Coast FIRE.
Before Coast FIRE, every dollar of spending competes with retirement savings. After Coast FIRE, you only need to earn enough to cover current expenses. You can take the pay cut, switch to part-time, pursue meaningful work with lower pay, or take a gap year. The retirement savings race is over. You just need to not spend your existing investments.
The formula
If you have $276,000 invested at age 40 and want to retire at 65, you don't need to save another cent. At 7% average annual growth, that $276,000 becomes $1,500,000 by the time you're 65. You just need to earn enough from work to cover day-to-day life.
What this changes practically
Before Coast FIRE, your relationship with work is defined by financial necessity — you need to earn enough to both live and save aggressively. After Coast FIRE, that pressure lifts entirely. Consider what that means:
- You can take a lower-paying job you find more meaningful without jeopardizing retirement
- You can go part-time — maybe 25–30 hours instead of 40–50
- You can take an extended sabbatical or unpaid leave
- You can move to a lower cost-of-living area and live on much less
- You can start a low-income creative project, business, or nonprofit
None of these require your savings to be "enough to retire on" — just enough to coast from today to retirement. That's often achievable in your 30s or early 40s for people who start early and save aggressively for a decade.
What makes Coast FIRE distinct from ordinary "financial cushion" thinking is the precision of the number. It isn't a vague sense of having "enough saved up" — it's a specific, calculable dollar figure tied to a specific retirement age and spending target, which means you can actually track progress toward it the same way you'd track progress toward full FIRE. That precision is what turns Coast FIRE from a nice idea into an actionable milestone with a real trigger point.
Calculate your Coast FIRE number
Sophie's Coast FIRE story
Sophie is 32. She's been working in marketing and saving aggressively — 40% of her $90,000 salary — for 8 years. Her portfolio is now at $310,000. She wants $1.8 million by age 65 (for $72,000/year spending at 4%). Her Coast FIRE number at 7% growth over 33 years: $310,000 ÷ (1.07)^33 = $310,000 ÷ 8.72 = $35,549.
Wait — she already has $310,000. She hit Coast FIRE years ago. Her money, left untouched at 7% average growth, will reach $1.8M by 65 without a single additional contribution. Sophie can now work a lower-paying job she actually loves, move part-time, or take a year off traveling. The only rule: don't touch the investments.
Coast FIRE doesn't mean stop earning. It means stop needing to save for retirement. You still need income to cover current living expenses. The freedom is that income no longer needs to include a retirement savings component — every dollar earned is available for present-day life.
The risks to watch
Coast FIRE works if the market delivers returns close to historical averages over your timeline. Some things to keep in mind:
- Return assumptions matter enormously. Using 8% vs 6% average returns changes your Coast FIRE number by nearly 40% over 25 years. Use conservative estimates (6%–7%) to build in margin.
- You can't touch the principal. The math only works if your investments keep compounding untouched. If you raid them for a car, home renovation, or emergency, the calculation breaks.
- Inflation erodes purchasing power. Build your FI target using inflation-adjusted spending and real (not nominal) return estimates, or your retirement number will be too small.
People calculate Coast FIRE using their current spending, then cut back to lower-income work that barely covers reduced expenses. The Coast FIRE target should use your planned retirement spending — often higher than your current lean years — not your current spending while in saving mode.
Your Coast number at every age, side by side
The exact dollar figure changes enormously depending on how many years you have left before your target retirement age — that's the whole mechanism of Coast FIRE. Here's the Coast FIRE number for someone planning to retire at 65, spending $60,000/year in retirement ($1.5M FI target), at a 7% assumed return, shown at different current ages:
- Age 25 (40 years to go): $100,171
- Age 28 (37 years to go): $122,713
- Age 30 (35 years to go): $140,494
- Age 32 (33 years to go): $160,852
- Age 35 (30 years to go): $197,051
- Age 38 (27 years to go): $241,396
- Age 40 (25 years to go): $276,374
- Age 42 (23 years to go): $316,420
- Age 45 (20 years to go): $387,629
- Age 48 (17 years to go): $474,862
- Age 50 (15 years to go): $543,669
Notice how much lower the number is at 25 than at 50 — roughly a fifth the size — for the exact same eventual $1.5M outcome. That's compound growth doing more of the remaining work the earlier you start. It's also why Coast FIRE is often described as a young person's milestone: the number required gets meaningfully bigger, and the number of remaining years to hit it gets meaningfully smaller, the later you start looking.
Why your return assumption changes everything
Coast FIRE numbers are extremely sensitive to the return rate you assume, because that rate gets raised to the power of however many years you have left. Using the same 35-year-old, $60,000/year retirement spend, retiring at 65 (30 years out), here's how the Coast number swings with the assumed return:
Going from a 7% to a 9% assumption cuts the required Coast number nearly in half — which should make you suspicious of anyone claiming they've already "hit Coast FIRE" using an aggressive 9%–10% return assumption. A more conservative 5%–6% real-world planning number gives you a margin of safety if the market underperforms during your coasting years, which is exactly when you have the least income to fall back on if the plan comes up short.
The trap of a moving target: "coast creep"
Coast FIRE calculations assume your future spending target stays fixed. In practice, life stages change spending — a first child, a larger home, aging parents who need support — and each of those raises your FI target, which raises your Coast number retroactively. Using the same 35-year-old example: at $60,000/year planned retirement spending, the Coast number is $197,051. Bump the planned spending to $80,000/year (a plausible shift if kids or a bigger house enter the picture) and the Coast number jumps to $262,734 — a 33% increase, for a plan that felt "done" the year before.
This doesn't mean Coast FIRE is unreliable — it means it should be treated as a number you revisit periodically, not a milestone you calculate once and forget. Anyone who declared Coast FIRE based on a lean, no-kids budget and then had their circumstances change should recheck the math before assuming the coasting phase is still safe.
What moving your retirement age does to the number
Coast FIRE and target retirement age are directly linked — pushing your retirement age out gives compounding more years to work, which lowers today's required number. Pulling your retirement age in does the opposite, sharply. Same 35-year-old, same $60,000/year spend, same 7% return:
- Retiring at 65 (30 years away): Coast number is $197,051
- Retiring at 55 (20 years away): Coast number is $387,629 — nearly double
This is the real trade-off behind Coast FIRE: it's not really "financial independence achieved," it's "financial independence achieved for a specific target date." Someone who hits Coast FIRE for a 65 retirement is nowhere close to Coast FIRE for a 55 retirement with the same portfolio. Be explicit about which target age you're solving for before you tell yourself you've arrived.
Nominal vs. real returns — a critical distinction
The formula box above uses a 7% nominal return, which is a common assumption for stock market growth before subtracting inflation. But your FI target — if you're expressing it in today's dollars — should be compared against a real (inflation-adjusted) return, not a nominal one, or you'll understate how much you actually need. Using a real return of roughly 4% (7% nominal minus ~3% average inflation) for the same 35-year-old, 30-years-to-retirement scenario, the Coast number rises to about $462,478 — more than double the nominal-rate figure. Mixing nominal returns with today's-dollar spending targets is one of the most common — and most consequential — errors people make when estimating their own Coast number.
Either use a nominal return rate (7–10%) against a future, inflation-inflated spending target, or use a real return rate (4–7%) against your spending target expressed in today's dollars. Mixing the two — a nominal return against a today's-dollars target — is the single most common Coast FIRE calculation error, and it always makes the plan look far more advanced than it actually is.
Coast FIRE isn't all-or-nothing: partial coasting
Many people don't fully stop saving the moment they cross their Coast number — they scale back instead of stopping entirely. A partial-coast approach might mean dropping from a 40% savings rate to a 10% savings rate rather than 0%, which builds in a cushion against sequence-of-returns risk during the coasting years and against the "coast creep" problem described above. It also softens the transition: going from maximizing every paycheck for savings to spending every extra dollar can be a psychologically jarring switch, even when the math says it's safe.
Two more Coast FIRE stories
Sophie's story showed someone who's already crossed the line. Most people aren't there yet — here's what the math looks like mid-journey.
Marcus is 45, earns well as a senior engineer, and wants to retire at 62 spending $90,000/year ($2.25M FI target). At 7% growth over his remaining 17 years, his Coast FIRE number is $712,292. His current portfolio sits at $480,000 — about 67% of the way there. He's not coasting yet, but he's close enough that he's started asking whether he could drop to a 4-day week now and still cross the Coast line within a couple of years on his current trajectory, rather than waiting until the number is fully hit before making any change.
Priya is 29, two years into her career, wants to retire at 60 spending a lean $45,000/year ($1.125M FI target). Her Coast number at 7% growth over 31 years is $138,120 — and her current portfolio is $60,000, about 43% of the way. She's not close to coasting yet, but the number itself is a useful planning anchor: it tells her exactly how much more she needs to accumulate before her ongoing contributions become optional, rather than leaving that milestone vague and unmeasured.
Both examples make the same point from opposite ends: Coast FIRE isn't just a binary "have I hit it or not." The percentage-of-the-way-there number is itself useful information, because it tells you how aggressively you still need to save versus how close you are to having options — and it gives you a concrete, revisitable checkpoint rather than a vague sense of "getting closer someday."
How to calculate your own Coast FIRE number, step by step
You don't need the interactive calculator above to do this by hand — the formula only has four inputs:
- Step 1 — Set your retirement spending target. Use your expected annual spending in retirement, not your current spending, expressed in today's dollars.
- Step 2 — Multiply by 25. This gives your full FI target under the standard 4% safe withdrawal rate assumption (25 = 1 ÷ 0.04).
- Step 3 — Count the years between now and your target retirement age. This is the exponent in the formula.
- Step 4 — Divide your FI target by (1 + assumed return) raised to that number of years. The result is your Coast FIRE number today.
Once you have that number, compare it to your current invested portfolio (retirement and brokerage accounts — not home equity or emergency fund, since those aren't compounding toward this specific goal in the same way). The ratio of current portfolio to Coast number is your percent-of-the-way-there figure, exactly like Marcus's 67% and Priya's 43% above.
Coast FIRE, Barista FIRE, and full FIRE — how they relate
These three terms get used interchangeably sometimes, but they describe different points on the same spectrum, not synonyms:
- Coast FIRE means your invested portfolio, left alone, will compound to your full retirement target by your target age. You still need to earn enough to cover current living expenses through work.
- Barista FIRE is a related but distinct concept — it typically describes having enough invested to cover part of your current expenses, with part-time or lower-stress work covering the rest, often specifically to keep employer health insurance. It doesn't require your portfolio to be large enough to eventually reach full FI on its own without further contributions.
- Full FIRE means your portfolio has already reached the size where a safe withdrawal rate covers 100% of your living expenses indefinitely, with no work income required at all.
Someone can be at Coast FIRE without being anywhere near Barista FIRE or full FIRE — Coast FIRE only promises that the retirement number arrives on schedule, assuming no further contributions and no withdrawals in the meantime. It says nothing about whether you could stop earning income today.
Frequently asked questions
Does Coast FIRE mean I can stop working entirely?
No — that's full FIRE, a different and larger milestone. Coast FIRE means you no longer need to actively save for retirement, but you still need income to cover your current cost of living until your target retirement date. The freedom Coast FIRE unlocks is about the kind of work you do and how much you're paid for it, not whether you work at all.
What if the market underperforms during my coasting years?
This is the central risk of Coast FIRE. If your portfolio grows slower than your assumed rate during the coast phase, you'll arrive at your target retirement age with less than planned. Using a conservative return assumption (5–6% rather than 8–9%) and rechecking your progress every year or two — rather than assuming the plan runs itself — are the main defenses against this risk.
Can I combine Coast FIRE with part-time or lower-paid work?
Yes — this is one of the most common ways people actually use Coast FIRE in practice. Once your invested portfolio no longer needs new retirement contributions, any income from part-time or lower-paid work only needs to cover your current living expenses, which is a much easier bar to clear than covering both living expenses and an aggressive savings rate.
Does Coast FIRE work if I still have debt?
High-interest debt (like credit cards) works against the same compounding math that makes Coast FIRE possible, so it generally makes sense to clear high-interest debt before or alongside pursuing Coast FIRE. Lower-interest debt, like a mortgage well below your expected investment return, is a more case-by-case judgment call and doesn't necessarily need to be paid off first.
What if I don't hit my Coast number by the age I hoped?
Nothing breaks — it just means you keep contributing a bit longer than you'd planned, or push your target retirement age out slightly. Because the Coast number shrinks the more years remain before retirement, even a few more years of contributions at a normal savings rate typically closes the gap faster than the raw dollar shortfall would suggest, since every dollar contributed late still gets whatever years remain to compound.
The bottom line
Coast FIRE is one of the more motivating milestones in FIRE planning precisely because it's reachable well before full retirement — often a decade or more earlier for people who save aggressively in their 20s and 30s. But it's a number worth treating with some humility: it's sensitive to your return assumption, it moves if your spending target moves, and it only tells you when your investments are done working, not when you're free to stop earning entirely. Calculate it honestly, recheck it periodically, and use it as a real decision tool for the work and lifestyle trade-offs it's meant to unlock.
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