Coast FIRE: The Number That Lets You Stop Saving for Retirement

Coast FIRE is the point where the money you have already invested will grow, with no further contributions, into the full amount you need to retire at your chosen age. Once you reach it, your paycheck only has to cover today's living costs. The formula is short: Coast number = your FIRE number ÷ (1 + real return)^{years to retirement}. In a hypothetical example, someone who needs $1,000,000 at 65 and assumes a 5% after-inflation return has reached Coast FIRE at 35 with about $231,400 invested. This page explains the math, shows the numbers by age, and covers what can go wrong.

The Short Answer

• What it is: enough invested today that compound growth alone reaches your retirement target by your retirement age. You can stop adding to retirement savings and simply cover your current bills.
• Step 1, your FIRE number: a common rule of thumb is annual retirement spending × 25, which is the same as a 4% first-year withdrawal. $40,000 a year of spending gives $1,000,000.
• Step 2, your coast number: divide the FIRE number by (1 + expected real return) raised to the number of years until retirement.
• The catch: the result swings enormously with the return you assume. At age 35, coasting to $1,000,000 at 65 takes about $131,400 at a 7% real return but $308,300 at 4%.
• Coasting is not quitting: you still need earned income for every year until you retire, and you still need a plan for health insurance before Medicare at 65.

Coast FIRE Calculator

Enter your age, target retirement age, expected annual spending in retirement, withdrawal rate, expected real return and what you have invested now. The calculator shows your coast number, whether you have reached it, and the age at which your current balance would be enough to coast. Results are hypothetical projections, not guarantees.

The Coast FIRE Formula

Two steps.

1. Your FIRE number is how much you need invested on the day you retire:

FIRE number = annual retirement spending ÷ withdrawal rate

At a 4% withdrawal rate that is spending × 25. The 4% figure is a planning rule of thumb from historical studies of U.S. stock and bond returns, not a guarantee, and some early retirers plan on a lower rate such as 3.5% because their money may have to last longer than 30 years. At 3.5%, $40,000 of spending needs about $1,142,900 instead of $1,000,000. You can test how different withdrawal rates would have held up in past markets with our retirement withdrawal calculator.

Count only the spending your portfolio must cover. If you expect a pension or Social Security, subtract that income first. Our guide to how much you need to retire walks through the spending estimate.

2. Your coast number is what that target is worth today, discounted by the growth you expect:

Coast number = FIRE number ÷ (1 + r)ⁿ

where r is the expected annual return after inflation and n is the years until retirement. Using an after-inflation ("real") return keeps everything in today's dollars, so you can compare the target with today's spending directly. This is compound interest run backwards.

Hypothetical example: you are 40, want to retire at 65 (n = 25), spend $40,000 a year in today's dollars, use a 4% withdrawal rate, and assume a 5% real return. FIRE number: $1,000,000. Coast number: $1,000,000 ÷ 1.05²⁵ = about $295,300. With that much invested, you could in theory stop contributing.

Coast FIRE Numbers by Age

Hypothetical coast numbers for a $1,000,000 target at age 65, in today's dollars. For a different target, scale proportionally: a $1,500,000 target needs 1.5 times each figure.

Hypothetical. Coast number = $1,000,000 ÷ (1 + real return)^{(65 − age)}, rounded to the nearest $100. Returns are assumptions, not forecasts.

Two patterns stand out. Time does the heavy lifting: at 5%, a 25-year-old needs less than a third of what a 50-year-old needs to coast to the same target. And the higher the assumed return, the smaller the number, which is exactly why the assumption deserves suspicion. To see how your current savings compare with typical balances, see average retirement savings by age.

The Return Assumption Changes Everything

Coast FIRE calculators often default to a 7% real return. That is an optimistic planning input for a stock-heavy portfolio, and it does not hold for a portfolio with bonds, or for a stretch of weak markets. Here is what happens if you plan on 7% and get less (hypothetical):

• At 35 you have $131,400, your coast number at 7%. You stop contributing.
• If the portfolio actually earns 6% real for 30 years, you reach about $754,500 at 65.
• If it earns 5%, you reach about $567,800, and at that rate you would not hit $1,000,000 until roughly age 77.

When Will You Reach Coast FIRE?

If you are still contributing, your balance and your coast number move toward each other: the balance grows from returns and new savings, and the coast number rises each year because there is one fewer year of growth left. The age at which they meet is your coast age.

Hypothetical example: you are 35 with $100,000 invested, add $10,000 a year, and target $1,000,000 at 65.

• At a 7% real return, the balance catches the coast number at about age 39, with roughly $175,500 invested.
• At a 5% real return, it takes until about age 57, with roughly $677,600 invested.

Same saver, same habits, an 18-year difference from a two-point change in the return assumption. Our FIRE calculator projects the full path to your FIRE number, including the coast point, if you want to model contributions year by year.

The Risks of Coasting

• Sequence of returns. The formula assumes a smooth average return every year. Real markets deliver it unevenly. A deep loss shortly after you stop contributing hurts more than the same loss decades later, because there is no new money buying at lower prices.
• Inflation. Using real returns handles average inflation, but your own retirement costs can rise faster than the CPI, especially for health care. Check that your spending estimate is still right every few years.
• Health insurance before 65. Medicare starts at 65 for most people. If coasting leads you to a lower-paid or part-time job without benefits, budget for marketplace or other coverage until then. Our guide to health care costs in retirement covers the pieces.
• Social Security is a bonus, not a given. Full retirement age is 67 for anyone born in 1960 or later, and you can claim as early as 62 at a permanent reduction. If you exclude Social Security from your FIRE number, any benefit you receive is a margin of safety. If you include it, use an estimate from your own SSA statement rather than an average. See the average Social Security check for context.
• Life changes. A divorce, a child, a disability or a job loss can draw down the balance you were counting on to grow untouched.

For the broader trade-offs of leaving full-time work early, read the pros and cons of early retirement.

Coast FIRE vs Lean, Barista and Fat FIRE

FIRE stands for "financial independence, retire early." The variants are informal community labels, not official terms, and people draw the lines differently. Broadly:

Coast FIRE is the least demanding milestone and often the first one people reach. Many treat it as permission to take a lower-paid job they prefer, cut hours, or redirect savings to other goals, rather than a reason to stop working.

Why It Still Pays to Keep Contributing

Reaching your coast number gives you the option to stop. It rarely makes sense to give up an employer match. A hypothetical example: on a $60,000 salary with a 50% match on the first 6% of pay, the employer adds $1,800 a year. Ten years of those match dollars alone, from 36 to 45, would grow to about $60,100 by 65 at a 5% real return, or about $96,200 at 7%. That money also makes up for a weaker-than-assumed return.

Other reasons to keep some savings going after reaching Coast FIRE:

• Buffer for low returns. Every extra dollar lowers the return you need to hit the target.
• Earlier optional retirement. Contributions move your FIRE date forward, so coasting at 40 can become retiring at 58 instead of 65.
• Tax breaks. For 2026 you can defer up to $24,500 into a 401(k); see the 2026 401(k) limits. A health savings account can also build a fund for those pre-Medicare years.

Sources & Methodology

• Medicare.gov, Get started with Medicare: Medicare eligibility at 65.
• 42 U.S.C. 416(l): full retirement age of 67 for people reaching 62 after 2021 (born 1960 or later), and the early retirement age of 62.
• IRS, 401(k) limit increases to $24,500 for 2026: the 2026 elective deferral limit.

Method notes. Every dollar figure on this page other than the 401(k) limit is our own arithmetic on hypothetical inputs. Coast numbers use annual compounding at a constant real return: Coast = Target ÷ (1 + r)ⁿ. The coast-age example adds $10,000 at the end of each year. Real returns of 4% to 7% are illustrative assumptions, not forecasts of what any portfolio will earn, and they ignore taxes and fees. The 4% withdrawal rate is presented as a common rule of thumb only.

This article is for general information and is not financial advice. Official figures were checked against the primary sources on 2026-10-04. All projections are hypothetical; actual investment returns vary, can be negative, and are not guaranteed. Consider a qualified advisor before cutting retirement contributions.

FAQ

What is Coast FIRE?
Having enough invested that, with no further contributions, growth alone will reach the amount you need to retire at your chosen age. After that, your income only has to cover your current living costs.

How do I calculate my Coast FIRE number?
First find your FIRE number: annual retirement spending divided by your withdrawal rate (spending × 25 at 4%). Then divide it by (1 + expected real return) raised to the number of years until retirement.

What return should I assume?
Use an after-inflation return, and be conservative. Over 30 years the coast number is more than twice as large at a 4% assumption as at 7%, so running two or three scenarios and planning on the higher number is safer than relying on one optimistic figure.

How much do I need to Coast FIRE at 30?
For a hypothetical $1,000,000 target at 65, about $93,700 at a 7% real return, $181,300 at 5% and $253,400 at 4%. Your number depends on your own spending and retirement age.

Is Coast FIRE the same as retiring?
No. You still need earned income to pay your bills until retirement age. It means you can stop saving for retirement, not stop working.

What is the difference between Coast FIRE and Barista FIRE?
With Coast FIRE your portfolio is left alone to grow and your job covers all current spending. With Barista FIRE you already draw on your portfolio for part of your spending and a part-time job covers the rest.

Should I count Social Security in my FIRE number?
You can subtract expected benefits from the spending your portfolio must cover, using the estimate on your own SSA statement. Leaving it out is more conservative and treats any benefit as a cushion. Full retirement age is 67 for anyone born in 1960 or later.

Should I stop contributing once I reach Coast FIRE?
You can, but keeping at least enough in to get any employer match is usually worth it. Extra contributions protect against weak returns and let you retire earlier than planned.

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"Coast FIRE: The Number That Lets You Stop Saving for Retirement." Wealthy Pot, 2026. https://wealthypot.com/coast-fire/