What Is Coast FIRE? Meaning, How It Works and Examples

Coast FIRE is the point where the money you have already invested will grow, with no new contributions, into enough to retire at your chosen age. Once you reach it, you stop saving for retirement and only earn enough to pay current bills. It is one of several flavors of FIRE (financial independence, retire early)^[1], and the one that frees you up soonest.

You do not quit working at Coast FIRE. You quit having to save. That can mean a lower-paid job you enjoy more, fewer hours, or a career break, as long as your income covers your spending. You will also see it written as Coast FI, CoastFI or coastfire; they all mean the same thing.

What does Coast FIRE mean in practice?

The name describes the feeling. Your portfolio has built up enough momentum that it can coast the rest of the way to retirement, the way a bike coasts downhill once you stop pedaling. Compounding does the work your contributions used to do.

What changes is how much you need to earn. Take a household that takes home $85,000 a year, invests $25,000 and lives on $60,000. At Coast FIRE the investing can stop, so the income they need drops by 29%, to $60,000. That gap is the room Coast FIRE creates: room to switch careers, cut hours, start a business or take time out for family.

What does not change:

• You still need income every year until your retirement age, enough to pay every bill including taxes and health insurance.
• The portfolio stays untouched. Withdrawing from it, even briefly, undoes the math.
• Your retirement date stays the same. Coast FIRE buys flexibility now, not an earlier full retirement. If you want that, you have to keep saving.

How do you calculate your Coast FIRE number?

Your Coast FIRE number is your full FIRE number discounted back to today at your expected real (after-inflation) return. There are two steps:

1. FIRE number = annual retirement spending ÷ safe withdrawal rate. At 4%, that is 25 times spending, the rule that traces back to William Bengen's 1994 research^[2].
2. Coast FIRE number = FIRE number ÷ (1 + real return)ⁿ, where n is the number of years until you retire.

We use a 3.79% real return in this guide: 7% nominal, minus 0.1% fees, adjusted for 3% inflation. That sits well below the S&P 500's 1928-2025 history^[3] and at the upper end of Vanguard's current 10-year forecasts, which run from 4.8%-6.8% a year for US stocks to 5.3%-7.3% for developed markets outside the US^[4]. If your retirement could last 50-60 years, research points to a 3.25%-3.5% withdrawal rate instead ^[5], which raises every number below by 14%-23%. The Coast FIRE calculator page derives the formula step by step and shows how Social Security and couples change it.

Worked example

Maya is 32 with $150,000 invested. She wants to retire at 62 on $45,000 a year and currently invests $25,000 a year.

• FIRE number: $45,000 ÷ 4% = $1,125,000
• Coast number today: $1,125,000 ÷ 1.0379³⁰ = $368,925
• She is $218,925 short today. If she keeps investing $25,000 a year, she reaches Coast FIRE at 43, when her coast number has risen to $555,243.

Her coast number rises as she gets older, because the money has fewer years left to compound, but her contributions push her balance up faster than the target rises. After 43, Maya could stop contributing entirely.

How much do you need to Coast FIRE at each age?

The table shows the Coast FIRE number for retiring at 65 at three spending levels. Every five years you wait, the number rises by about 20%, because the money has five fewer years to compound.

Does Coast FIRE really work?

It worked in most of history, but not all of it, and the length of the coast matters. We replayed every historical period in Damodaran's 1928-2025 data^[3] and asked one question: did a lump sum, left alone in an annually rebalanced 80% stock / 20% bond portfolio with 0.1% fees, grow at least as much as our 3.8% assumption?

• 35-year coasts (for example, 30 to 65): 100% of 64 periods made it. The worst, starting in 1956, still grew 4.4x after inflation versus 3.7x needed. With 60/40 instead, the hit rate drops to 91%.
• 25-year coasts (for example, 40 to 65): 82% of 74 periods made it. The worst, starting in 1957, grew only 1.7x versus 2.5x needed.

So Coast FIRE is most reliable when you hit it young. If you coast later, aim above your number or keep a small contribution going. The bigger risk comes at the end: returns in the first decade of retirement drive how much you can safely spend^[6], which our 4% rule research guide covers in depth. These are US results; other markets have had different, often weaker, histories.

How big a cushion should you have before you coast?

Starting to coast with exactly your number means you need your assumed return, every year on average, for the whole coast. Starting with more lowers the return you need. The table shows what a cushion buys, using the same 80/20 historical test as above.

Over a long coast, a modest cushion closes most of the historical gap: with 20% extra, a 30-year coast only needs 3.16% a year instead of 3.79%. Over 20 years, even a large cushion leaves real failures in the record, because a single bad decade weighs much more. That is the main reason late coasters keep investing something.

How do you decide when to start coasting?

Hitting the number is necessary but not enough. Before you cut your savings to zero, check six things:

1. You are above your number with a cushion that suits the length of your coast, as in the table above.
2. Your emergency fund is separate and full. If a job gap forces you to sell investments, you are no longer coasting.
3. You have a health insurance plan for the work you are moving to (see below).
4. Big future costs are budgeted elsewhere. A house, children or education are not in your retirement number, so they need their own savings or income.
5. Your new income reliably covers your spending, including taxes, with some slack.
6. You know when your money becomes available. Most withdrawals from 401(k)s and IRAs before 59½ face a 10% additional tax unless an exception applies^[7], so a coast plan with an early retirement age needs accessible savings for the gap.

Coasting does not have to be all or nothing. You can cut contributions in stages, or keep investing just enough to collect an employer match if you have one, and drop the rest.

What kinds of jobs do people coast with?

Any work that pays your current bills can be a coast job. What changes is that pay no longer has to include savings, so other things can come first. Common patterns include:

• The same field, fewer hours. Part-time, a four-day week or a job share in the work you already know.
• A lower-pressure role. Stepping back from management, on-call duty or long commutes to an individual or local role.
• Contract and freelance work. Consulting in your field lets you choose how much to take on, though income is less predictable.
• Seasonal or project work. Working part of the year and taking the rest off.
• A career change. Work you find meaningful but that pays less, such as teaching, nonprofits or a trade you always wanted to learn.
• Your own business. Coasting removes the pressure for the business to pay well from day one, as long as it covers your bills.

When you compare options, look past the salary. Ask whether the job offers health coverage, whether it keeps your skills marketable in case you need to earn more later, and whether the income is steady enough to never touch the portfolio.

How do you handle health insurance while coasting?

In the US, health insurance is often the deciding factor, because part-time, freelance and small-business work may not come with employer coverage. If you leave a job and lose employer coverage, you can qualify for a Special Enrollment Period to buy a Marketplace plan outside the usual enrollment window; dropping COBRA voluntarily does not qualify^[8]. Medicare starts at 65^[9], so if your coast years end before then, budget for premiums in both your coasting income and your retirement spending.

Should your Coast FIRE number include Social Security?

Usually yes, because ignoring it overstates what you need by a wide margin. Social Security is paid for life and adjusted for inflation, so every dollar of benefit is a dollar your portfolio does not have to fund. The catch is timing: if you stop full-time work at 65 but claim at 67, your portfolio pays your full spending for those two years.

Take the 30-year-old from the table who wants $40,000 a year from 65. Without Social Security, the coast number is $272,322. Counting a $22,000 benefit from 67 drops it to $134,450. If you only trust 75% of that benefit, the number is $168,918, which is still far below the no-benefit figure.

Benefits depend on your claiming age: full retirement age is 67 for anyone born in 1960 or later, claiming at 62 cuts the benefit by 30%, and waiting until 70 adds 24%^[10]. Young savers often leave it out entirely as a hidden safety margin, then add it once their earnings record is longer. Either choice is reasonable as long as you know which one you made.

Coasting itself can change the benefit. It is based on your highest 35 years of wage-indexed earnings, and missing years count as zero^[11]. A few lower-paid coast years matter little if you already have 35 solid years, but stepping out of paid work in your 30s can leave zeros in the average. Check your earnings record and re-estimate once your plans are clear.

Can one partner coast while the other keeps working?

Yes, and for many couples it is the most practical version. The household reaches Coast FIRE together, because the portfolio and the retirement budget are shared, but only one income is needed to cover current bills. Often the partner with employer health coverage keeps working, and the other cuts back or changes careers.

Social Security helps here. A partner with a small earnings record can receive up to 50% of the other's full benefit as a spousal benefit at full retirement age, and a surviving spouse can receive up to 100% of the deceased worker's benefit^[10]. The Coast FIRE calculator has a couples mode that puts both partners' ages and benefits on one timeline.

What happens when you reach your retirement age?

Coast FIRE retirement looks like any other retirement: at your target age, your coast portfolio should have grown into your full FIRE number, and you start withdrawing from it. From that day the rules of the 4% rule apply, including the risk that a bad first decade forces you to spend less. The safe withdrawal rate calculator helps you pick a rate for your horizon.

If your balance is ahead of plan when you get there, you can retire earlier or spend more. If it is behind, the same levers as during the coast apply: work a little longer, spend a little less, or add part-time income, which turns your plan into Barista FIRE for a few years.

What are the pros and cons of Coast FIRE?

What can go wrong while you coast?

• Returns below your assumption. Check yearly whether your balance is still above the coast number for your current age. The calculator page shows how to run that yearly check and what to do after a bad year.
• Lifestyle creep. If retirement spending rises, so does the target. Re-run the math after big life changes.
• Raiding the account. Coast FIRE only works if the money is left alone, so keep a separate emergency fund.
• Health costs. If you leave an employer plan while coasting, budget for buying your own coverage until Medicare at 65.
• Skills going stale. If you step far back from your career, it can be harder to earn more later if you need to.

What do people get wrong about Coast FIRE?

• “Coast FIRE means retiring early.” It means you stop saving early. Full retirement still happens at the age you planned.
• “Once I hit the number, I'm done.” The number is a moving target that rises every year by your real return. You have to stay above it, not just touch it once.
• “The number is the same for everyone my age.” It scales directly with your retirement spending and depends heavily on your return assumption and retirement age.
• “Coasting means not working.” That is closer to Barista or full FIRE. Coasting means your work pays your bills and nothing more is required of it.

Is Coast FIRE right for you?

Coast FIRE suits people who saved hard early, are still decades from retirement, and want their next decade to look different: less pressure, different work or more time. It works best with steady, modest spending and a job market where you can always earn enough to cover it.

It suits you less if your income is volatile, your future spending is very uncertain, or your coast would be short. In those cases, keep saving toward full FIRE, or plan on Barista FIRE, which draws on the portfolio and part-time income together.

Coast FIRE vs Barista FIRE vs full FIRE

All three use the same math but stop at different points. Here is what each costs for the same 35-year-old who wants to spend $50,000 a year, with full retirement at 65.

Our calculation, 3.79% real return, 4% withdrawal rate. Coast FIRE needs the least money but the most years of work. Full FIRE needs the most money and no work. For the full target behind all three, see how to calculate your FIRE number, and for a deeper look at the two part-way options, read Coast FIRE vs Barista FIRE.