Coast FIRE Calculator
How much do you need invested todayso that compound growth alone — no more contributions, ever — gets you to a full retirement? Enter your numbers and find out whether you're already coasting.
Coast FIRE Calculator
Find the balance that lets you stop contributing today and still retire on time — compound growth does the rest.
Retirement and brokerage accounts only — not home equity or cash you plan to spend.
Use a real (after-inflation) return — 5–7% is typical for a stock-heavy portfolio — so spending stays in today's dollars.
In today's dollars.
The classic 4% rule is the default; early retirees often use 3–3.5%.
Your Coast FIRE Number (today)
$140,494
Full FIRE Number (at 65)
$1,500,000
Your Assets at 65 (no new contributions)
$1,067,658
Not coasting yet
You need $40,494 more invested today to coast. Without further contributions your $100,000 grows to about $1,067,658 by age 65 — short of your $1,500,000 target. Keep contributing and re-check as your balance grows.
What is Coast FIRE?
Coast FIRE (Financial Independence, Retire Early) is the moment your invested assets become a self-driving retirement plan. The balance is big enough that compound growth, left alone for the years between now and your retirement age, will reach your full retirement number without a single additional contribution.
You still work — Coast FIRE doesn't pay today's bills. But the retirement problem is solved. That changes what kind of work you have to do: a lower-paying job you love, a part-time schedule, a risky startup, a few years as a stay-at-home parent. None of them endanger retirement anymore, because retirement no longer needs your paycheck.
It's the purest demonstration of why starting early matters. A 25-year-old needs far less to coast than a 45-year-old targeting the same retirement, because their money gets twenty extra years of compounding.
The Coast FIRE formula
Two steps. First, your full retirement (FIRE) number:
At the classic 4% rule that's simply 25× your annual spending. Then discount it back to today at your expected return:
Where r is your expected annual return (as a decimal) and tis the number of years between your current age and retirement age. If your invested assets are at or above that number, you've hit Coast FIRE — compounding will do the rest of the saving for you.
A worked example
Maya is 30, plans to retire at 65, and wants $60,000/year in retirement (today's dollars). She assumes a 7% real return and the 4% rule.
Step 1 — FIRE number: $60,000 ÷ 0.04 = $1,500,000.
Step 2 — discount it back 35 years: $1,500,000 ÷ 1.0735= $1,500,000 ÷ 10.68 ≈ $140,500.
If Maya has $140,500 invested at 30, she never has to save for retirement again. With $150,000 she's already past it — that balance compounds to about $1.6 million by 65 on its own. With $100,000, she's about $40,500 short: it would grow to roughly $1.07 million, not $1.5 million, so she keeps contributing and re-checks each year.
Getting the assumptions right
- Use a real return, not a nominal one.Your target spending is in today's dollars, so the growth rate must be after inflation. Historical S&P 500: ~10% nominal, ~7% real. Plugging in 10% with today's-dollar spending will dramatically understate your Coast FIRE number.
- Match the withdrawal rate to retirement length. The 4% rule was tested on 30-year retirements. Retiring at 50 or earlier? Run it again at 3.5% and see how the number moves.
- Coast FIRE is a moving target. Lifestyle inflation raises your target spending, which raises both numbers. Re-run the math once a year or after any big life change.
- Sequence risk still exists. The formula assumes a smooth average return; real markets deliver lumpy ones. Being modestly above your Coast FIRE number — not exactly at it — is the safer place to make decisions from.
What hitting Coast FIRE actually buys you
Coast FIRE is less a finish line than a permission slip. People who reach it typically use the freed-up savings rate to:
- Downshift to less stressful or more meaningful work
- Redirect savings to a house down payment, college funds, or a business
- Take a mini-retirement or extended family leave
- Simply spend more today, knowing future-you is already taken care of
One keep-contributing exception: if your employer matches 401(k) contributions, capture the full match even after you coast. A 50–100% instant return beats any spreadsheet.
Related Tools & Articles
Retirement Savings Calculator
Project your nest egg with ongoing contributions and the 4% rule
Compound Interest Calculator
Model any balance, rate, and term with a year-by-year chart
Investing at 25 vs. 35
Why ten early years are worth more than thirty late ones
401(k) Growth Calculator
Model employer match and pre-tax growth to retirement
Frequently Asked Questions
What is Coast FIRE?
Coast FIRE is the point where your invested assets are large enough that, with no further contributions, compound growth alone will carry them to a full retirement nest egg by your target retirement age. Once you hit it, you only need to earn enough to cover your current living expenses — every retirement dollar is already in the market doing its job.
How is Coast FIRE different from regular FIRE or Barista FIRE?
Regular FIRE means your portfolio can fund your living expenses right now, so you can quit working entirely. Barista FIRE means your portfolio covers most expenses and a part-time job fills the gap. Coast FIRE is the earliest milestone of the three: you still work to pay today's bills, but you never have to save another retirement dollar.
What rate of return should I use?
Use a real (after-inflation) return so your target spending stays in today's dollars. The S&P 500 has returned roughly 10% per year historically, or about 7% after inflation. A 5–7% real return is a reasonable range for a stock-heavy portfolio; use the lower end if you want a conservative plan or hold significant bonds.
Is the 4% rule safe for an early retirement?
The 4% rule comes from the Trinity Study, which tested 30-year retirements. If you'll be retired for 40–50 years, many planners suggest a more conservative 3–3.5% withdrawal rate. Lowering the rate raises your FIRE number — and therefore your Coast FIRE number — so it's worth running the calculator at both 4% and 3.5% to see the range.
What counts as invested assets for Coast FIRE?
Count money that's invested and earmarked for retirement: 401(k), IRA, Roth IRA, HSA (if you'll use it for retirement healthcare), and taxable brokerage accounts. Don't count your emergency fund, home equity you'd have to live in anyway, or cash you plan to spend before retirement.
Should I actually stop contributing once I hit Coast FIRE?
Not necessarily — and at minimum, keep contributing enough to capture any employer 401(k) match, which is an instant 50–100% return. Hitting Coast FIRE is best treated as flexibility, not a finish line: it means you could take a lower-paying job, work part-time, or redirect savings toward other goals without endangering retirement.