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Coast FIRE is the point where your portfolio is large enough to grow to your full FI number on its own — no more contributions required. It unlocks lifestyle flexibility and reduced work pressure years before traditional retirement.
Coast FIRE is a milestone in the journey to financial independence. You reach it when your investment portfolio has grown large enough that compound growth alone — without any additional contributions — will carry that portfolio to your full FI number by your target retirement age. After reaching your Coast number, you can dramatically reduce savings pressure. You still need to work enough to cover current living expenses, but the retirement race is effectively won.
The name comes from the nautical metaphor: you have done the hard paddling, and now you can let the current carry you. Your portfolio "coasts" to retirement on its own momentum.
Regular FIRE (Financial Independence, Retire Early) requires accumulating enough to fund your entire retirement immediately. Coast FIRE only requires accumulating enough so that future compound growth handles the rest. The distinction matters because Coast FIRE is achievable much sooner — sometimes 10 or 15 years before full FI — and opens up significant lifestyle flexibility well before traditional retirement.
With regular FIRE, you need $1,500,000 before you can stop working (using $60k/year at 4% withdrawal). With Coast FIRE, you might only need $300,000 saved at age 35 — because that $300,000 will compound to $1,500,000 by age 60 without another dollar added. The trade-off: you still need earned income to cover living expenses during the coast period.
The formula uses the concept of present value — specifically, what amount of money today, growing at a given rate, will equal your target in the future:
Coast Number = FI Number ÷ (1 + r)^years
Where the FI Number is your full FIRE target (annual expenses ÷ withdrawal rate), r is your expected annual real return rate as a decimal, and years is the number of years until your target retirement age. This is simply discounting your FI number back to the present at your expected growth rate.
You can also rearrange this to find how many years until you reach Coast FIRE from your current balance, or what return rate you need to reach a given Coast number in a given time — useful for stress-testing your plan.
Let's walk through a complete example. Suppose you are 35 years old, you expect to spend $65,000 per year in retirement, and you plan to retire at 60. You will use a 4% withdrawal rate and assume 7% real annual returns.
Step 1 — Calculate your FI number: $65,000 ÷ 0.04 = $1,625,000.
Step 2 — Calculate years to retirement: 60 − 35 = 25 years.
Step 3 — Calculate your Coast number: $1,625,000 ÷ (1.07)^25 = $1,625,000 ÷ 5.427 = approximately $299,500.
This means if you have $299,500 invested at age 35 and earn an average 7% real return, your portfolio will grow to $1,625,000 by age 60 without another contribution. If your portfolio is already at $299,500, you have reached Coast FIRE. You still need to work — but only enough to cover your current expenses, not to fund retirement savings.
Coast FIRE's primary appeal is the lifestyle flexibility it unlocks long before full retirement. Once you reach your Coast number, you no longer need a high-income job. The career choices that were previously required for aggressive savings become optional. You might:
Take a lower-paying job that is more fulfilling or less stressful. Work part-time or reduce to four days per week. Start a passion project or small business without needing it to be highly profitable. Spend more time with family without the guilt of "I should be saving more." Move to a lower cost-of-living area where a modest income is sufficient.
The psychological benefit is substantial. Many high earners feel trapped in stressful, demanding careers because they feel they cannot afford to leave before reaching full FI. Coast FIRE offers an earlier exit from that pressure.
These two terms are often confused or conflated, but they describe different things. Coast FIRE is a number — a specific portfolio balance that makes additional contributions unnecessary for meeting your retirement target. Barista FIRE is a lifestyle strategy — working a lower-stress, lower-income job in semi-retirement that covers living expenses while your portfolio grows.
Many people pursue both simultaneously: they save aggressively until they hit their Coast number, then transition to a Barista FIRE lifestyle — lighter work that covers current expenses while the portfolio coasts. The term "Barista FIRE" comes from the idea of taking a job at a coffee chain that offers health insurance, solving the healthcare coverage problem that challenges many early retirees.
The primary risk of Coast FIRE is that your portfolio may underperform your assumed return. If markets average 5% instead of 7% over the next 25 years, your $299,500 grows to only $1,014,000 instead of $1,625,000 — a $611,000 shortfall. You would then need to resume contributions or delay retirement. This is why conservative return assumptions and periodic recalculation are important.
Lifestyle inflation is a second risk. The mental shift from aggressive saver to "I only need to cover current expenses" can cause spending to drift upward. If your annual expenses increase, your FI number rises, and your original Coast calculation is no longer valid. Tracking actual spending and rechecking your Coast number annually keeps you honest.
Coast FIRE is most appealing to people who feel burned out by high-income, high-stress work and have already accumulated a meaningful portfolio. It rewards early and aggressive savers — the faster you accumulate, the sooner you can coast and the longer you can enjoy the lifestyle flexibility it provides.
It is less suitable if you have a very short runway to retirement (fewer than 10 years), because the compounding does not have as much time to work and the Coast number is nearly as large as the full FI number. For those with long timelines — 20 or 25+ years — Coast FIRE can be a transformative milestone that changes the character of your working life well before full financial independence.
Put it into practice
Calculate how your current investments grow toward your Coast FIRE number using real compounding math.
Coast FIRE is the point at which your current investment portfolio is large enough that compound growth alone will carry it to your full financial independence (FI) number by traditional retirement age — without any additional contributions. Once you reach your Coast number, you only need to earn enough to cover current living expenses. You can stop aggressively saving, work less stressful jobs, or reduce hours while letting the market do the heavy lifting.
The Coast FIRE formula is: Coast Number = FI Number ÷ (1 + r)^years. Your FI number is your full FIRE target (annual expenses ÷ withdrawal rate). 'r' is your expected annual real (inflation-adjusted) return rate, and 'years' is the number of years between now and your target retirement age. For example, if your FI number is $1,500,000, you expect 7% real returns, and you have 25 years to retirement, your Coast number is: $1,500,000 ÷ (1.07)^25 = $1,500,000 ÷ 5.427 = approximately $276,500.
After reaching Coast FIRE, you stop (or dramatically reduce) new contributions. Your existing portfolio continues to grow through compound returns. As long as your actual returns match your assumed growth rate, the portfolio should reach your full FI number at your target retirement age. You do not withdraw from the portfolio during the coast phase — you simply stop adding to it. You still need to earn enough through work or other income to cover your current living expenses during this period.
Coast FIRE is a financial milestone — the portfolio size that allows compound growth to do all remaining work. Barista FIRE is a lifestyle strategy — a semi-retirement where you stop high-stress work and take a lower-income job (famously, something like working at Starbucks) that covers current expenses while your portfolio continues to grow. Many people achieve Coast FIRE and then transition to a Barista FIRE lifestyle, but they are distinct concepts: one is a number, the other is a life design choice.
Most Coast FIRE calculators use 7% as the assumed real (inflation-adjusted) annual return, which approximates the long-term historical average of U.S. equity markets after inflation. For a more conservative estimate, use 5% or 6%. The return rate you choose has a large impact on your Coast number: at 5% real returns with 25 years to retirement, the discount factor is lower, so you need a higher starting balance to reach the same FI number. Conservative assumptions are generally wiser for long-horizon planning.
The main risks are market underperformance and lifestyle inflation. If markets return significantly less than your assumed rate, your portfolio may not reach your FI number by your target date, requiring either additional contributions or a delayed retirement. Lifestyle inflation is also a risk: once you stop aggressively saving, there is a psychological tendency to increase spending, which simultaneously reduces savings and potentially raises your FI number. Having a clear plan and regularly checking your portfolio progress against your projected trajectory helps manage both risks.
Calculate the full FI number that serves as the target in your Coast FIRE calculation.
Read guide →The research behind the withdrawal rate used to determine your FI number.
Read guide →How to choose the right withdrawal rate for your retirement timeline and risk tolerance.
Read guide →