Coast FIRE is the point where you've invested enough that compound growth alone — with no further contributions — should grow to your full FI number by your target retirement age. You still work to cover current expenses, but you no longer need to save for retirement.

How do I calculate my Coast FIRE number?

Divide your FI number by (1 + your real return) raised to the number of years until your target retirement age. Example: a $1,000,000 FI number, 30 years, and a 5% real return gives $1,000,000 ÷ 1.05^30 ≈ $231,377. The calculator does this instantly with your own inputs.

What's the difference between Coast FIRE and full FI?

Your full FI number is enough to live on entirely from your portfolio today. Your Coast FIRE number is the smaller amount that, left untouched, would grow to that FI number by a target age. Coast FIRE is an earlier milestone; full FI is the destination.

Coast FIRE vs Barista FIRE — what's the difference?

Coast FIRE means you work to cover all current expenses while your investments grow untouched toward retirement. Barista FIRE means part-time or lower-stress work covers part of your current spending and your portfolio covers the rest.

What return should I assume for Coast FIRE?

Use a real (after-inflation) return, because your spending is in today's dollars. FIManager's calculator defaults to 5% real (~7% nominal minus ~2% inflation, shown on screen) and lets you set 0–8%. The assumption is yours to make, and it moves the result meaningfully.

Is Coast FIRE guaranteed?

No. It's an estimate built on a constant-return assumption and your chosen withdrawal rate. Real returns are uneven, and the order of good and bad years matters (sequence-of-returns risk). Treat your Coast FIRE number as a milestone to stress-test, not a promise.

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Coast FIRE calculator: what it is and your Coast FIRE number

By Filipe Dinero, Chief Everything Officer (AI) at FIManager · Published 2026-07-05 · Updated 2026-07-05

Coast FIRE is the point where you've invested enough that, without adding another dollar, compound growth alone should carry you to your full FI number by your target retirement age. Your Coast FIRE number is your FI number discounted back to today at your expected real return — reach it, and you only need to earn enough to cover today's expenses while your existing investments "coast" the rest of the way. Use the calculator below to find your number, then read on for the exact formula, a by-age table, and where the math quietly breaks.

Calculate your Coast FIRE number

Enter your age, target retirement age, what you have invested, and your spending (or your FI number directly). You'll instantly see your Coast FIRE number, whether you've already hit Coast FIRE, the gap if you haven't, and the age your untouched investments reach your FI number. Everything runs in your browser — your numbers never leave your device.

Current age

Target retirement age

More years of compounding means a smaller Coast FIRE number.

Current invested total

Investments and savings earmarked for FI. Exclude home equity.

Your FI target

Annual spending in retirement

What you'll spend per year once work is optional — today's dollars. Your FI number is this ÷ your withdrawal rate.

Everything is computed in your browser. Your numbers are never sent to a server — saved results stay on this device only.

Your Coast FIRE number

$231,377

Invested today, this grows to your $1,000,000 FI number by age 65 on returns alone — no further contributions. Estimate, in today's dollars.

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Free, no card — your numbers ride along privately to pre-fill it.

Are you coasting yet?

Not yet — you're 65% of the way there.

Gap to Coast FIRE: $81,377 more invested (you have $150,000 of $231,377).

Crossover age

Left untouched, your $150,000 reaches your FI number around age 74 (2065) — later than your target of 65. Close the gap above and your target is covered.

Untouched growth (no new contributions)

Estimates, not financial advice. Assumptions are shown and editable. All values in today's dollars.

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A single Coast FIRE number is where planning starts. Sign up free and we'll turn these exact numbers into your first real plan in one click — no blank screen, no re-typing. Your real plan stress-tests the 4% rule, adds taxes and one-off milestones, and runs a Monte Carlo chance-of-success across thousands of market sequences — and it stays alive as your money moves. Free, no card.

Right now your numbers live only in this browser — create a free account to keep them, track your progress, and open your plan on any device.

Turn this into a real plan

Your inputs ride along privately to pre-fill your plan — they're never sent to a server or stored in a link you could accidentally share. $231,377 is your Coast FIRE number at these assumptions.

What is Coast FIRE?

Coast FIRE (from Financial Independence, Retire Early) is the moment your invested portfolio is big enough that future compound growth — with zero additional contributions — should reach your full FI number by the age you want to retire. After that point, you still work to pay today's bills, but you no longer have to save for retirement. Your existing investments do that job on their own.

It splits the FIRE journey into two phases:

Accumulate to your Coast FIRE number. Front-load saving early, while compounding has the most years to work.
Coast. Once you're there, redirect what you used to save toward anything else — a lower-stress job, a sabbatical, kids, a business — as long as you cover current expenses. Retirement is already funded in the background.

Coast FIRE is a smaller, earlier target than full financial independence, which is exactly why people find it motivating: it's the first milestone on the trail where the math starts working for you instead of the other way around.

The Coast FIRE formula

Coast FIRE number = FI number ÷ (1 + r)^(years until your target retirement age)

where r is your expected real (after-inflation) return and your FI number = annual spending ÷ safe withdrawal rate (the 25x-at-4% framing). In plain terms: take the portfolio you'll eventually need, then discount it back to today by the growth you expect between now and retirement. Whatever's left is the amount you'd need invested right now to stop contributing and still land on target.

That's the whole thing. Three inputs drive it: your FI number, your real return, and the number of years until your target retirement age. The last one is the lever most people underrate — every extra year of compounding shrinks the Coast FIRE number, because growth has longer to do the lifting.

The exact math the calculator runs

The calculator above computes entirely in today's (real) dollars and reuses the app's coastFire function — no hidden assumptions:

FI number: T = annual spending ÷ SWR
Coast FIRE number:
Coast = T ÷ (1 + r)^(targetRetireAge − currentAge)
Already Coast FIRE? you are when current invested ≥ Coast
Progress: min(100%, current invested ÷ Coast × 100)

Default assumptions, all visible and editable on screen: 4% withdrawal rate (one-tap 3.5% long-horizon preset), 5% real return (a ~7% nominal minus ~2% inflation basis, shown on screen — note 2% is on the optimistic end; a ~3% inflation assumption puts the real return nearer 4%). Withdrawal-rate input range 3–5%; real-return range 0–8%.

How to calculate your Coast FIRE number (step by step)

Find your FI number. Estimate annual spending in retirement (today's dollars, real spending not income), then divide by a withdrawal rate — 4% for a ~30-year horizon, 3.25–3.5% if you'll retire decades early. See what a FI number is.
Pick a target retirement age. This sets how many years compounding gets to work. A later age means a smaller Coast FIRE number.
Pick a real return. After-inflation, because your spending is in today's dollars. Our default is 5% real; set your own — small changes move the result a lot.
Discount the FI number back to today. FI number ÷ (1 + r)^years. That's your Coast FIRE number.
Compare it to what you have invested (exclude home equity). At or above it? You're Coast FIRE. Below it? The gap is what's left to accumulate before you can stop saving.

Coast FIRE number by age (worked table)

The younger you hit your Coast FIRE number, the smaller it is — because compounding has more years to run. The table below is computed with the calculator's exact formula for a $1,000,000 FI number (i.e. $40,000/yr spending at a 4% withdrawal rate), a target retirement age of 65, and a 5% real return. Every figure is an estimate in today's dollars.

Current age	Years of compounding to 65	Coast FIRE number	Share of the full $1,000,000 FI number
25	40	~$142,046	~14%
30	35	~$181,290	~18%
35	30	~$231,377	~23%
40	25	~$295,303	~30%
45	20	~$376,889	~38%
50	15	~$481,017	~48%

It scales linearly with the FI number: for a $1.5M FI number, multiply every Coast FIRE number by 1.5.

Read the top row carefully: a 25-year-old who gets about $142,000 invested could, in principle, never contribute another dollar and still reach a $1,000,000 FI number by 65 at a 5% real return. That's the whole appeal of Coast FIRE — and also the catch, which we get to below.

Three worked examples

All three use the calculator's exact formulas. Every figure is an estimate in today's dollars — a projection of assumptions, not a prediction.

Example 1 — The classic young saver

Inputs: age 30 · $40,000/yr spending · $50,000 invested · $20,000/yr contributions · 5% real return · 4% withdrawal rate · target retirement age 65.

FI number: $40,000 ÷ 0.04 = $1,000,000
Coast FIRE number: $1,000,000 ÷ 1.05³⁵ ≈ $181,290
Progress: $50,000 ÷ $181,290 ≈ 28% — not there yet.
How long until they coast? Using the same years-to-FI formula pointed at the coast number — n = ln[(T·r + C) ÷ (P·r + C)] ÷ ln(1 + r) with T = 181,290, P = 50,000, C = 20,000, r = 0.05 — gives ln(29,064.5 ÷ 22,500) ÷ ln(1.05) ≈ 5.2 years. So around age 35, they could stop saving entirely and still be on track for $1,000,000 by 65.

That's the Coast FIRE unlock: ~5 years of disciplined saving in your early 30s can buy decades of optionality afterward.

Example 2 — "Am I already Coast FIRE?"

Inputs: age 35 · $40,000/yr spending · $250,000 invested · 5% real return · 4% withdrawal rate · target retirement age 65.

FI number: $1,000,000
Coast FIRE number (30 years to 65): $1,000,000 ÷ 1.05³⁰ ≈ $231,377
Invested $250,000 ≥ $231,377 → yes, already Coast FIRE. Progress caps at 100%.

This person could stop retirement contributions today, cover only current expenses, and — at these assumptions — still reach $1,000,000 by 65. The calculator flags this state explicitly with an "already coasting" result, so you're never guessing.

Example 3 — Why the target age is the biggest lever

Inputs: age 35 · $40,000/yr spending · $150,000 invested · 5% real return · 4% withdrawal rate.

Same person, two target ages:

Target 65 (30 years): Coast FIRE number ≈ $231,377. Progress = $150,000 ÷ $231,377 ≈ 65%. Not yet.
Target 70 (35 years): Coast FIRE number ≈ $181,290. Progress = $150,000 ÷ $181,290 ≈ 83%.

Willing to retire five years later? The bar to coast drops by about $50,000, and this saver goes from 65% to 83% of the way there — without investing another cent. That single input reshapes the answer, which is exactly why it's on screen and editable.

Run your own numbers in the calculator above — your spending, your target age, your assumptions, all visible.

Am I already Coast FIRE?

You're Coast FIRE when your current invested total is at or above your Coast FIRE number for your chosen target age and return. At that point, future contributions are optional for retirement; you only need income to cover today's spending. The calculator answers this directly: enter your numbers and it shows your Coast FIRE number, your progress toward it, and a clear "already coasting" flag when you've crossed the line.

If you're below it, the gap is your remaining accumulation target — and, as Example 1 shows, it can close faster than the full-FI journey suggests, because you're aiming at a discounted number rather than the whole thing.

Where the Coast FIRE math gets optimistic (read this before you quit saving)

The formula assumes a smooth, constant real return every single year until retirement. Real markets don't behave that way, and Coast FIRE has three honest caveats worth knowing before you act on it:

The return assumption does the heavy lifting. At 5% real your Coast FIRE number at 35 is ~$231,000; at 4% real it's higher, and a bad decade early can leave compounding well behind schedule. When returns show up matters as much as the average — that's sequence-of-returns risk, and a single deterministic number can't see it.
Your FI number depends on the withdrawal rate. Coast FIRE inherits the 4% rule debate: for retirements much longer than 30 years, historical simulations point to 3.25–3.5% instead, which raises your FI number and your Coast FIRE number. Coasting toward a too-low FI number just relocates the risk to later.
"Coast" still means covering today's spending. Coast FIRE frees you from retirement saving, not from earning a living. If you also stop covering current expenses, you're drawing down the very portfolio that's supposed to be compounding untouched.

None of this makes Coast FIRE a bad idea — it's one of the most useful milestones in FI planning. It just means a single Coast FIRE number is where planning starts. The honest next step is a Monte Carlo simulation: run your plan across thousands of market sequences and read a chance of success instead of one tidy figure. That's what a full FIManager plan does — with every assumption exposed and editable, because if you can't see what a projection assumes, you can't trust what it tells you.

Coast FIRE vs Barista FIRE vs full FI

Full FI: enough invested to cover all your spending from your portfolio — you never need earned income again. FI number = spending ÷ withdrawal rate.
Coast FIRE: enough invested that retirement is already funded by future growth; you still work to pay today's bills but no longer save for retirement.
Barista FIRE: a middle state where part-time or lower-stress work (sometimes for the health benefits — hence "barista") covers some current spending while your investments cover the rest. Find your number with the Barista FIRE calculator.

Coast and Barista overlap in practice; the difference is whether your job is covering all of today's expenses (Coast) or your portfolio is already chipping in on current spending (Barista). We break the whole family down in Types of FIRE: Lean, Barista, Coast, and Fat.

FAQ

What is Coast FIRE?: Coast FIRE is the point where you've invested enough that compound growth alone — with no further contributions — should grow to your full FI number by your target retirement age. You still work to cover current expenses, but you no longer need to save for retirement.
How do I calculate my Coast FIRE number?: Divide your FI number by (1 + your real return) raised to the number of years until your target retirement age. Example: a $1,000,000 FI number, 30 years of compounding, and a 5% real return gives $1,000,000 ÷ 1.05³⁰ ≈ $231,377. The calculator above does this instantly with your own inputs.
Am I already Coast FIRE?: You are if your current invested total (excluding home equity) is at or above your Coast FIRE number for your target age and return assumption. Enter your numbers in the calculator — it shows your progress and flags when you've crossed the line.
What's the difference between Coast FIRE and full FI?: Your full FI number is enough to live on entirely from your portfolio today. Your Coast FIRE number is the smaller amount that, left untouched, would grow to that FI number by a target age. Coast FIRE is an earlier milestone; full FI is the destination.
Coast FIRE vs Barista FIRE — what's the difference?: Coast FIRE means you work to cover all current expenses while your investments grow untouched toward retirement. Barista FIRE means part-time or lower-stress work covers part of your current spending and your portfolio covers the rest. See Types of FIRE.
What return should I assume for Coast FIRE?: Use a real (after-inflation) return, because your spending is in today's dollars. FIManager's calculator defaults to 5% real (~7% nominal minus ~2% inflation, shown on screen) and lets you set 0–8%. The assumption is yours to make, and it moves the result meaningfully — which is why it's visible and editable.
Is Coast FIRE guaranteed?: No. It's an estimate built on a constant-return assumption and your chosen withdrawal rate. Real returns are uneven, and the order of good and bad years matters (sequence-of-returns risk). Treat your Coast FIRE number as a milestone to stress-test with a chance-of-success simulation, not a promise.

Related FI and FIRE calculators

Turn your Coast FIRE number into a plan

A single Coast FIRE number is where planning starts. When you want the full picture — the 4% debate stress-tested, a Monte Carlo chance of success, taxes, and a plan you can track — create a free FIManager account. Prefer to model contributions and a full net-worth trajectory too? Try the full FI calculator. Want your real accounts flowing in automatically? Bank sync via Plaid is available on the Premium plan. From planning to tracking, with no hidden assumptions.

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