Coast FIRE is the point where your current investments, left alone, will compound into a full retirement, so you keep working, but only because you want to.
Key Takeaways
- Coast FIRE number = your target retirement pot ÷ (1 + expected return)years remaining. Invest that much today and stop: math does the rest.
- At 7% average annual real growth, a 52-year-old targeting $1.75 million by 67 needs about $634,000 invested right now, with nothing more added.
- The strategy runs on one input you can’t buy back: time. Compress the runway from 30 years to 15 and the number needed today roughly doubles for the same target.
- Unlike Barista FIRE, Coast FIRE doesn’t require dropping to part-time work. You keep the salary, you just stop feeding the portfolio.
- The 4% withdrawal rule underneath all of this traces to William Bengen’s 1994 research and the 1998 Trinity Study, which tested 30-year retirements, a better match for a 67-year-old’s retirement than a 35-year-old’s (thepoorswiss.com).
- Financial Samurai puts $300,000 invested as a rough floor for calling yourself Coast FIRE: a personal-finance blogger’s rule of thumb, not an industry standard (financialsamurai.com).
- Coast FIRE, Barista FIRE and Chubby FIRE aren’t rival philosophies. They’re stages. Most people who reach one pass through another on the way somewhere else.
What Is Coast FIRE?
Coast FIRE is the point where the money you’ve already invested, left completely alone, will grow into a full retirement by the age you’ve picked. You stop adding to your 401(k) or brokerage account and just let compounding finish the job. The “work-optional” part is real: you can keep your job, cut your hours, switch to something that pays less but annoys you less, or do nothing different at all. The portfolio no longer cares.
The term comes from the FIRE community itself: r/coastFIRE has north of 149,000 members trading spreadsheets on exactly this question, and it sits deliberately apart from traditional FIRE, where you need 25 times your annual spending invested today, no further growth required, no more paycheck needed ever (Financial Samurai). Coast FIRE is the patient cousin: you’ve done the hard savings work, and now you get to stop grinding and start waiting.
Worth saying plainly, because the personal-finance internet loves a strict rule: nobody is coming to check your brokerage statement. This isn’t a club with a membership card. It’s a math threshold you either cross or haven’t, and the only person keeping score is you at 2am doing the spreadsheet again.
How Do You Calculate Your Coast FIRE Number?
The formula, borrowed from the same 25x logic behind traditional FIRE: take your target retirement number, then discount it backward by however many years of growth you have left before you plan to actually retire.
| Step | What you need | Formula |
|---|---|---|
| 1 | Your FIRE number | Annual retirement spending × 25 |
| 2 | Years left to coast | Target retirement age − your current age |
| 3 | Your Coast FIRE number | FIRE number ÷ (1 + growth rate)years |
Here’s what that looks like for someone starting where a lot of this site’s readers are actually starting: not 30, not 25 years out.
Run that: $1,750,000 ÷ (1.07)15 ≈ $634,000. Get $634,000 invested and untouched at 52, and 7% average annual growth carries it to $1.75 million by 67, with zero further contributions required. Everything you earn between now and then is yours to spend, save faster, or downshift with. I built an actual Coast FIRE calculator so you can run your own numbers instead of borrowing mine: my $70,000 and your $70,000 are almost certainly not the same $70,000.
Confidence level: medium. The 7% figure sits close to the S&P 500’s long-run inflation-adjusted average of 7.62% a year since 1945 (officialdata.org), so it’s a reasonable planning assumption, not a guarantee. Fifteen-year windows have delivered real returns well above and well below that average depending on when they started. Treat the $634,000 as a planning estimate to stress-test, not a number to bank on.
How Does Coast FIRE Compare to Barista FIRE, Chubby FIRE, and the Rest?
The FIRE community’s naming habit is half the fun and half the confusion. Here’s the actual taxonomy, roughly ordered from least to most money required.
| Variant | Rough annual spending | Portfolio needed | Still earning income? |
|---|---|---|---|
| Lean FIRE | Under ~$40,000 | Under ~$1,000,000 | No |
| Coast FIRE | Your eventual target | Whatever compounds to it by your target age | Yes, full-time, by choice |
| Barista FIRE | Any, part-covered by work | Smaller than full FIRE, topped up by part-time pay | Yes, part-time |
| Traditional FIRE | Your actual number | 25× annual expenses, today, in full | No |
| Chubby FIRE | $80,000–$200,000 | ~$2,000,000–$5,000,000 | No |
| Fat FIRE | $200,000+ | $5,000,000+ | No |
Notice Coast FIRE and Barista FIRE aren’t on the same axis as the others. They’re stages, a point in your working life, not a spending level. You can be Coast FIRE on your way to a Lean, Chubby or Fat number. My own semi-retirement research and the broader financial independence guide on this site both sit in the same neighborhood: different entry points into the same underlying idea: money buys you the option to say no, before it buys you anything else.
Why Does the Math Change When You’re Starting at 50?
Every Coast FIRE calculator assumes one input you can’t top up: time. A 30-year-old with a 35-year runway can coast on a modest number, because compounding has decades to work. Compress that same target into 15 years and the required starting amount roughly doubles, not because you’re spending more but because the exponent in the formula got smaller.
Here’s the part nobody selling the 30-year-old version of this mentions: it also works in your favor once you flip to actually spending the money. The Trinity Study’s famous 4% rule was tested against 30-year retirement horizons (thepoorswiss.com). A 35-year-old retiring early needs the withdrawal math to hold for 50-plus years, genuinely uncharted territory for that research. A 67-year-old drawing down for 20-25 years is retiring into exactly the horizon the 4% rule was built and tested for. Starting later isn’t only a disadvantage. It’s also the version of this plan the underlying math was actually designed to answer.
What Are the Risks Nobody Mentions?
Sequence-of-returns risk is the big one. The 7% average in the worked example above is exactly that: an average. If the market drops 20% in the first two years after you stop contributing, your portfolio starts its compounding climb from a smaller base, and the tidy 15-year timeline stretches. Averages smooth out real history; your actual 15 years will not look like the average.
Healthcare is the other one, and it’s bigger for this age group than any spreadsheet admits. If Coast FIRE means dropping to part-time or self-employed work before 65, you lose employer coverage and land in the individual market until Medicare eligibility. I’ve gone deep on the actual numbers on that gap in the Barista FIRE piece. Read that before you hand in your notice, not after.
Confidence level: medium. Historical average returns are a reasonable planning input, not a forecast. Nobody, not me, not a calculator, not a fee-only advisor with a nice office, can tell you what the market does in your specific 15 years. Build a buffer into your number rather than coasting to the exact dollar the spreadsheet spits out.
Is Coast FIRE Right for You at 50-Plus?
It suits people who already have real money working for them and want the pressure gone more than they want the number bigger. If most of your net worth sits in a 401(k) you’ve been feeding steadily for 20-plus years, run the calculator. You may already be closer to coasting than your day-to-day stress level suggests.
It doesn’t suit people who haven’t started, or who are meaningfully behind where they’d hoped to be by now. That’s a different problem, with a different toolkit, not a moral failing. My pieces on building a 6-month exit plan and running a portfolio career after 50 both start from “behind” and work forward, which is a more useful starting point than a coast calculation that just confirms the bad news. For the fuller picture of what “buying your options back” looks like at this age, the Money After 50 hub is where I keep the whole map, and the wealth section covers what to do with the working years themselves, not just the exit from them.
My own version of this, for what it’s worth, is somewhere in the middle, documented here if you want the unfiltered version, blood clots and all.
Coast FIRE: Questions People Actually Ask
What’s a good Coast FIRE number if you’re starting in your 50s?
There’s no single number. It depends on your target retirement age, your expected annual spending, and how many years you have left to coast. A 52-year-old planning to retire at 67 on $70,000 a year needs roughly $634,000 invested today, assuming 7% average annual growth. Someone with a 25-year runway or a leaner budget needs far less. Run your own inputs through the calculator rather than borrowing this example.
Does Coast FIRE mean you stop contributing to retirement accounts entirely?
That’s the strict version: you stop adding new money and let compound growth do the work alone. Plenty of people run a softer version: they keep contributing enough to capture a full 401(k) match, since that’s free money, and simply stop pushing beyond it.
Can you Coast FIRE without ever having done an aggressive savings push?
You can arrive at a Coast FIRE number through years of ordinary saving rather than an extreme frugality phase. It’s the amount already invested that matters, not the intensity of how you got there. A steady 10-15% savings rate over two decades gets plenty of people to their number without ever living on rice and beans.
What happens to Coast FIRE if the market drops right after you stop contributing?
This is the real risk: sequence-of-returns risk. A bad few years right after you stop adding money, before compounding has had time to work, can push your target date out further than a smooth-average projection suggests. It’s a reason to build in a buffer, not a reason to dismiss the strategy.
Is Coast FIRE the same as quiet quitting?
They get confused because both involve doing less than maximum effort at work, but they’re not the same. Quiet quitting is disengaging from a job while still needing the paycheck. Coast FIRE is a financial position: the paycheck becomes optional for retirement funding, even if you still show up fully and even still like the job.
Do you need a financial advisor to plan a Coast FIRE strategy?
Not to do the math itself; a spreadsheet or a calculator handles that. A fee-only fiduciary advisor earns their cost when the picture gets complicated: pensions, Social Security timing, a spouse with a different retirement date, or tax-bracket management during the coast years. For a straightforward single-income case, most people can plan this themselves.
How is Coast FIRE different from just under-saving and hoping?
The math. Under-saving is a guess; Coast FIRE is a calculation you can check against your own numbers, with a specific dollar figure, a specific growth assumption, and a specific target date attached. Run the number. If you haven’t, you’re not coasting. You’re drifting and calling it a strategy, which is a much worse story to be telling yourself at 52.
Methodology. The $634,000 worked example uses a $70,000 annual spending target, the standard 25× FIRE-number multiple, a 15-year runway from age 52 to 67, and a 7% average annual growth assumption, chosen to sit conservatively below the S&P 500’s measured 7.62% long-run real return since 1945 (officialdata.org). The 4% withdrawal rule and its 30-year test horizon trace to William Bengen’s 1994 paper and the 1998 Trinity Study, as summarized by thepoorswiss.com.
I skipped Reddit as a data source for claims or statistics; the single r/coastFIRE link above exists only to evidence how the community actually uses the term, not as a source for any number in this piece. No financial, tax, or investment advice. The worked numbers are a planning illustration, not a recommendation for your specific situation.
