July 13, 2026 · 10 minute read
By Nethaven Team · Personal finance research & product team
Coast FIRE Explained: How to Find Your Coast Number
Coast FIRE means you've invested enough that growth alone reaches your FIRE number. At a 5% real return, $200,000 at 32 can grow to $1M by 65, no new deposits.
Coast FIRE is the point where your investments are large enough that compound growth alone can reach your FIRE number by your target date, without another contribution. You still work to pay the bills, but you can stop saving for retirement. At a 5% real return, about $200,000 at age 32 grows to $1,000,000 by 65.
Most people picture financial independence as one distant finish line. There is an earlier line that gets far less attention, and it changes careers more often than the famous one. Once your portfolio can grow into your FIRE number on its own, every dollar you earn only needs to cover the life you are living now. That milestone is Coast FIRE, and for a 32-year-old targeting $1,000,000 at 65, it can sit around $200,000, a fifth of the headline goal.
What is Coast FIRE in plain language?
Coast FIRE means you have already invested enough that time and compounding will finish the job. You are not financially independent yet; you still need a paycheck for rent, groceries, and everything else. What you no longer need is to save for retirement. The portfolio is on autopilot, coasting toward the target while you cover only the present.
That single change quietly rewrites your relationship with work. A job that must fund your current life is a much smaller ask than one that must fund your current life plus a seven-figure goal. Need a concrete test? If you could drop your retirement contributions to zero tomorrow and still hit your number on schedule, you have coasted.
How is Coast FIRE different from full FIRE?
Full FIRE requires a portfolio that can pay for your life immediately, typically about 25 times annual spending under the 4% rule. Coast FIRE only requires the seed of that portfolio, planted early enough to grow. Same destination, very different arrival dates.
| Milestone | What it means | What becomes optional |
|---|---|---|
| Coast FIRE | Growth alone reaches the target on time | Retirement saving |
| Barista FIRE | Part-time income plus withdrawals cover life | Full-time work |
| Full FIRE | Withdrawals alone cover life | All work |
The order matters. Everyone on a FIRE path passes through Coast FIRE first, usually years before full independence, whether they notice the crossing or not. Noticing is the useful part.
The Coast FIRE formula: why time does the heavy lifting
Compounding is exponential, so the years furthest from your target date are the most valuable ones. At a 5% real (after-inflation) return, money roughly doubles every 14 years, a pace you can verify with the SEC's compound interest calculator. A dollar invested at 32 doubles twice by 60-something; a dollar invested at 55 doubles once, if that. This is why the coast number depends so heavily on how far away the target date is:
| Years until target | Needed today to coast to $1,000,000 (5% real) |
|---|---|
| 10 years | ~$614,000 |
| 15 years | ~$481,000 |
| 20 years | ~$377,000 |
| 25 years | ~$295,000 |
| 33 years | ~$200,000 |
The formula behind the table is one line: divide the FIRE number by (1 + real return) raised to the years remaining. Using real returns keeps everything in today's dollars, so you can compare the coast number directly against your current portfolio balance.
What does Coast FIRE look like with real numbers?
Take the worked example we use across this series. Maya is 32, spends $40,000 a year, has $100,000 invested, and adds $12,000 a year. Her FIRE number at a 4% withdrawal rate is $1,000,000, and at a 5% real return her contributions carry her there in about 27 years.
Her Coast FIRE number for a work-optional age of 65 is $1,000,000 ÷ 1.05³³, roughly $200,000. She is halfway there at 32 without thinking about it. If she keeps investing $12,000 a year, her balance crosses the coast threshold around age 43 at roughly $342,000. From that day forward, every remaining contribution is acceleration, not necessity: she could redirect the $12,000 toward a career change, a smaller workload, or simply an earlier date, and $1,000,000 by 65 would still arrive on its own.
You can reproduce every number in this example with the FIRE Path Explorer. Enter your annual spending, current portfolio, yearly contribution, and a real return assumption; it returns your FIRE number, your estimated independence year, and the coast amount for that same timeline.
What does reaching Coast FIRE actually buy you?
Not idleness. Income. Specifically, it returns the slice of income that retirement saving was consuming, and it removes the career pressure that comes with a decades-long savings obligation.
- Flexibility in spending. A saver putting away $12,000 a year who coasts can absorb a $12,000 hit to income or expenses without touching the plan.
- Lower pressure. Market dips feel different when you need growth eventually rather than contributions now. So do layoffs.
- Career choice. Work that pays less but means more becomes affordable. The portfolio no longer cares which job covers your groceries.
What are the limits and risks of coasting?
A coast plan leans on market growth for decades, and decades are long enough for assumptions to break. Treat these four honestly before you stop contributing:
- Investment risk. A 5% real return is an assumption, not a promise. A long stretch of weak markets can leave the portfolio short with little time to recover, which is why conservative assumptions beat optimistic ones here.
- Spending changes. The FIRE number is built from today's spending. Kids, housing, or lifestyle growth raise the target, and a raised target un-coasts you retroactively.
- Taxes. Withdrawals from pre-tax accounts are taxable income. If your spending figure ignores that, your real target is higher than the one you coasted to.
- Healthcare. Anyone stepping back from full-time work before traditional retirement age needs a plan for insurance, and it is rarely cheap.
The practical defense is monitoring, not pessimism. Coast FIRE is a threshold you hold, not a box you tick once, so check your real balances against the coast line at least yearly. A net worth view that updates from your actual accounts makes that a glance instead of a spreadsheet session, and portfolio tracking keeps the "invested today" input honest.
Check your Coast FIRE amount
You may be closer to this milestone than you think, especially if you started investing in your twenties. Open the FIRE Path Explorer, enter your real numbers, and compare the coast amount it reports against your current portfolio. Then keep reading the series: how the 4% rule sets the target this whole calculation aims at, and where passive income fits once the portfolio starts doing the earning. New to the framework? Start with our beginner's guide to FIRE.
Educational content, not personal financial advice. Projections assume constant returns and cannot guarantee any outcome.
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Frequently asked questions
What is Coast FIRE?
Coast FIRE is the point where your invested portfolio is large enough that compound growth alone can carry it to your FIRE number by your target date, with no further contributions. You still work to cover current living expenses, but you no longer need to save for retirement. The finish line funds itself.
How do I calculate my Coast FIRE number?
Divide your FIRE number by growth over the years remaining: FIRE number ÷ (1 + real return) ^ years. Someone targeting $1,000,000 in 33 years at a 5% real return needs about $200,000 invested today. The FIRE Path Explorer computes this automatically from your spending, portfolio, and return assumptions.
What is the difference between Coast FIRE and regular FIRE?
Full FIRE means your portfolio can cover your spending right now, so work is optional immediately. Coast FIRE means your portfolio will get there on its own by a future date, so only retirement saving is optional. Coast FIRE arrives years or decades earlier because compounding does the remaining work.
Can I stop investing completely after reaching Coast FIRE?
Mathematically yes, that is the definition, but most people keep contributing something. Stopping entirely leaves no margin for weak markets, higher future spending, or a revised retirement date. Treat the coast threshold as a milestone that buys flexibility, not a command to stop. Even small ongoing contributions rebuild your buffer.
What return should I assume for a Coast FIRE projection?
Use a real (after-inflation) return so every number stays in today's dollars. Many planners model 4% to 5% real for a diversified stock-heavy portfolio, well under the U.S. market's long-term average, to leave a margin of safety. A higher assumption shrinks your coast number on paper but raises the odds reality falls short.
Does Coast FIRE account for taxes and healthcare?
Not by itself, and both matter. The projection says nothing about the taxes you will owe on withdrawals or the cost of health insurance before traditional retirement benefits begin. Build both into the annual spending figure that sets your FIRE number, and revisit the plan as your real costs become clearer.
Is Coast FIRE risky?
The main risks are a long stretch of below-average returns, spending that grows faster than planned, and the temptation to stop saving with no buffer. A coast plan leans entirely on market growth for decades, so conservative return assumptions, an honest spending number, and periodic check-ins against your real portfolio balance are essential.