Calculate the portfolio you need today so compound growth alone funds your retirement — no more contributions required.
Coast FIRE is the inflection point every aggressive saver is working toward. Once you hit it, you can stop optimizing every dollar and start living on your own terms. This calculator finds that number, shows you the gap or surplus, and projects the year you'll arrive.
Direct answers to the most common questions, in plain language. Skim if you're in a hurry; dig deeper below.
The portfolio size that compounds to your FIRE number without any new contributions.
Coast FIRE is the point at which your invested assets — if left completely alone — will grow to your full financial independence number by retirement age, purely through compound growth. Once you hit it, you only need to earn enough to cover living expenses. You stop "building wealth" and simply coast.
Full FIRE number ÷ (1 + real return)^(years to retirement).
Your full FIRE number is your desired annual retirement spending divided by your safe withdrawal rate. The Coast FIRE number discounts that backwards using your expected real (after-inflation) return. For example, if your full FIRE number is $1.5M and you have 25 years at 5% real return, your Coast FIRE number today is roughly $444,000.
The percentage of your portfolio you can spend per year without running out of money.
The 4% rule — drawn from the Trinity Study — suggests a retiree can withdraw 4% of their starting portfolio annually (inflation-adjusted) and not run out of money over a 30-year retirement. More conservative retirees use 3–3.5%; those retiring for 40+ years often use 3.5% or lower. The SWR you choose directly sets your FIRE number.
No. Lean and Fat FIRE differ on spending level; Coast FIRE differs on savings behavior.
Lean FIRE, regular FIRE, and Fat FIRE are about how much you spend in retirement (less, average, or more). Coast FIRE is a strategy about when you can stop actively saving. You might be Lean FIRE and Coast — meaning you only need a modest portfolio, and you reached the coast point years ago. Or you might be Fat FIRE and still coasting toward a $3M target.
The mechanics in short answers — no jargon, no upsell.
If you want $60,000/year and you use a 4% SWR, your full FIRE number is $1,500,000. That is the portfolio that could sustain you indefinitely, assuming historical market returns hold.
Using your expected real (after-inflation) return as the discount rate, the calculator computes how much you need today so that compound growth alone closes the gap by retirement age. The earlier your current age, the smaller the Coast FIRE number — time is the multiplier.
After reaching the Coast FIRE number, you only need to cover your living expenses. Your invested assets do the heavy lifting. You have essentially "pre-funded" retirement and can trade saving aggressively for working on your own terms.
The Coast FIRE target curve drops as you age (because you need less time for growth). The "no contribution" line shows where your current portfolio goes with zero new savings. The "with savings" line shows your trajectory if you keep contributing at your current rate.
Designed so anyone can model their situation in under a minute, with or without a finance background.
Most calculators show retirement balance. This one shows the actual milestone that matters: when compound growth can carry you the rest of the way.
Once you hit your Coast FIRE number, you can take a lower-stress job, go part-time, or take a career detour — guilt-free. The math is locked in.
Dollars invested in your 20s and 30s are worth exponentially more than dollars invested in your 50s. Coast FIRE makes that visible and motivating.
Retirement age, real return, and spending level each move the Coast FIRE number dramatically. The calculator quantifies the trade-offs instantly.
Dial down the real return from 5% to 3% and see how your required Coast FIRE number changes. Build in margin before you declare yourself coasting.
Enter your annual savings and see exactly which year you will hit the Coast FIRE milestone — and what age you will be when it happens.
Everything you might ask before, during, or after using this tool.
Tax-advantaged accounts (401k, IRA, Roth IRA, HSA) and taxable brokerage accounts — any dollars genuinely invested in the market. Exclude your primary home equity, cash savings accounts, and physical assets. Those are not compounding at market rates, and the Coast FIRE math assumes your money grows at your chosen real return rate.
This calculator is built around real (after-inflation) returns because you are also entering spending in today's dollars. If you use nominal returns (e.g., 10%), you would also need to enter future spending in future (inflated) dollars, which is harder to reason about. Stick to real returns — 4–6% covers most long-run equity scenarios.
Lean FIRE targets minimal spending in retirement (say, $30,000/year); Fat FIRE targets abundant spending ($100,000+ /year). Both are about your eventual portfolio size. Coast FIRE is a different dimension entirely: it is the point in your accumulation phase at which you can stop contributing and let compounding finish the job. You can be Lean FIRE and still coasting, or Fat FIRE and not yet coasting.
The 4% rule comes from the Trinity Study (1998) and has been broadly validated for 30-year retirement horizons using US equity returns. For longer retirements (40+ years) or higher equity valuations, many planners now use 3.5% or even 3.25%. This calculator lets you adjust the SWR — if you plan to retire early, consider 3.5% as your baseline and treat 4% as the optimistic scenario.
Because time is doing less work. At age 30 with 35 years to retirement, your money has 35 years to compound. At 50, it only has 15. The Coast FIRE number at each age is the present value of the full FIRE number, discounted at your real return rate. Less compounding time means a higher current-dollars requirement — so the coast target curve rises as you age.
This is the core risk. If real returns average 2% instead of 5% for a decade, your portfolio may not reach the full FIRE number by retirement. The safest approach: build a margin of safety into your coast number, use a conservative real return assumption (3–4%), and plan to do occasional check-ins. If you are significantly ahead of the coast target, you have a buffer. If the gap closes, resume contributions for a few years.
Yes. Roth IRA contributions compound tax-free and are part of your investable base. Some Coast FIRE planners keep a mental distinction between pre-tax (traditional 401k/IRA) and post-tax (Roth) assets because withdrawals are taxed differently in retirement. For the Coast FIRE number itself, it is simpler and accurate enough to include all tax-advantaged accounts together — then separately verify your tax diversification.
Sequence risk matters most in the 5–10 years around retirement — a market crash in that window can permanently damage your withdrawal capacity. Coast FIRE does not eliminate this risk; it just ensures your accumulation math works if average returns hold. To manage sequence risk: maintain 1–3 years of cash as a buffer near retirement, consider a bond tent strategy (temporarily shifting toward bonds around your retirement date), and avoid locking in big spending commitments right as you hit your target.
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These terms get conflated constantly, and conflating them leads to bad planning. Here is the clean breakdown.
Lean FIRE and Fat FIRE are about the size of your eventual retirement portfolio — specifically, how much you want to spend each year in retirement. Lean FIRE usually means $25,000–40,000/year; Fat FIRE usually means $100,000+/year. Where you land on that spectrum determines your full FIRE number.
Coast FIRE is something else. It is a point in time during your accumulation phase — the moment your existing invested assets are large enough that, with no further contributions and assuming market returns hold, they will grow to your full FIRE number by retirement. After that point, you only need to cover current living expenses. You are done with the aggressive wealth-building phase.
You can aim for Lean FIRE and coast early (smaller target, potentially coast by 35). You can aim for Fat FIRE and never formally coast at all (the target keeps moving). The two dimensions — how much you need and how you get there — are orthogonal.
The Coast FIRE math makes something viscerally clear: a dollar invested at 28 is worth vastly more than a dollar invested at 48. At a 5% real return, $1 invested at 28 with a 37-year runway to age 65 becomes roughly $6. The same $1 invested at 48 with a 17-year runway becomes only $2.30.
This is why the FIRE community often pushes hard on savings rate in the early years. Getting to $200,000 invested by age 32 — even if you never save another cent — can mean your retirement is effectively funded, depending on your spending targets.
Practically, this means: prioritize your 401k to the employer match immediately, then max your Roth IRA, then go back to the 401k. Do this before lifestyle inflation has a chance to absorb your raises. The first decade of compounding is worth more than the last two decades combined.
Nominal return is what you see in a fund's fact sheet — say, 10% average annualized. Real return subtracts inflation: if inflation runs at 3%, your real return is about 7%. This calculator defaults to 5% real return, which roughly corresponds to a 7–8% nominal return with 2–3% inflation stripped out.
The reason to work in real returns: your spending target is in today's dollars. If you want $60,000/year in today's purchasing power, and you work in real returns, the math stays clean throughout. There is no separate step to inflate future spending.
If you prefer to think in nominal terms, enter your nominal return and also adjust your spending target upward for inflation by your expected retirement date. For a 30-year horizon at 3% inflation, $60,000 today becomes roughly $145,000. That approach is correct — it is just easier to make errors, which is why this calculator defaults to the real-return framework.
Declaring Coast FIRE does not mean quitting your job. It means the pressure to maximize your savings rate is gone. That is a significant psychological shift.
Many people who hit Coast FIRE stay in their careers but switch to work they find more meaningful, take lower-stress roles, go part-time, or spend a few years living abroad. The key is that they are no longer optimizing every financial decision around "how does this grow my net worth faster?"
There are real risks to be aware of. Health insurance is the practical one — if you coast before Medicare eligibility at 65, you need a plan for coverage. ACA marketplace plans are accessible but the premiums add up. Some coasters maintain part-time work partly for employer benefits. Others build health insurance premiums directly into their required annual income target.
The other risk is psychological. After years of aggressive saving, many people find it genuinely difficult to stop, even when the math says they should. That is not irrational — market downturns after declaring coast can feel catastrophic. The answer is to build a margin of safety into your coast number and keep periodic check-ins on your projections.
Coast FIRE assumes your portfolio averages a certain return over decades. But markets do not deliver smooth, average returns. They deliver volatile, lumpy returns in a specific order — and that order matters enormously near retirement.
A large market drop in the first few years of retirement is far more damaging than the same drop in the middle of retirement. Why? Because you are withdrawing from a shrunken base, and those early withdrawals at depressed prices lock in losses that cannot recover.
The standard mitigations: first, maintain a cash buffer of 1–2 years of spending as you approach retirement so you can ride out a short downturn without selling equities. Second, consider a bond tent — temporarily increasing your bond allocation in the 5 years before and after retirement, then slowly reducing it back. Third, keep flexible spending where possible: if markets drop sharply in year one of retirement, cutting discretionary spending by 15–20% for a year or two dramatically reduces sequence risk.
Coast FIRE is a starting-point calculation, not a guarantee. Revisit your projections every few years and stress-test at 3% real return, not just 5%.
Two short notes worth reading before you trust any number on this page.
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