Coast FIRE Calculator
See how much you need invested today to coast to retirement without another contribution.
Updated · By Teodor-Cristian Lutoiu
At a 7% real return, a 30-year-old with a $1.5M FIRE target at age 65 needs roughly $140,000 invested today to coast — no further contributions required. The same target at age 40 needs ~$275,000; at 50, ~$540,000. Miss the window and you can't coast — you have to keep contributing.
Fill in all five fields to see your coast number.
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See also
What Coast FIRE means
Traditional FIRE (Financial Independence, Retire Early) asks: how much do I need invested to stop working forever? The number is often 25–30× your annual expenses, following the 4% rule. It's a big target.
Coast FIRE is a less extreme version. It asks a different question: how much do I need invested today so that, even if I never add another dollar, compound growth alone gets me to full FIRE by my target retirement age?
Once you hit your coast number, your current savings will grow into your full FIRE number by age X. From that moment on, every dollar you earn from work only needs to cover your current living expenses. Save if you want to retire earlier or have a larger cushion — but you don't have to.
This is a less exhausting, less all-or-nothing framing. A lot of people hit Coast FIRE in their late 20s or 30s and feel permission to relax, drop to part-time, switch careers, or take a sabbatical without derailing their retirement.
Formula
The math is one line:
coast_number = fire_number ÷ (1 + real_return)^years_to_retire
This is compound interest run backwards. If you need $1,500,000 in 30 years and expect 7% real returns, today's coast number is $1,500,000 ÷ 1.07³⁰ ≈ $197,031. If you have $197,031 invested today and never add another cent, 30 years of 7% compounding gets you to $1,500,000.
Your coast age is the other half of the picture — given what you have today, at what age will your portfolio reach the full FIRE number if you stop contributing?
coast_age = current_age + log(fire_number / current_savings) / log(1 + real_return)
If coast_age ≤ target retirement age, you're already coasting. Contributions from here are optional.
Why "real" return, not nominal?
Stock market returns over long periods average about 10% nominal. But inflation averages about 3%. The real (inflation-adjusted) return is closer to 7%.
If you compute your coast number using 10% instead of 7%, you'll underestimate what you need — because the $1,500,000 you're targeting in today's dollars has to grow to offset 30 years of inflation as well. Using a real return and targeting your FIRE number in today's dollars keeps the math honest and comparable across decades.
Conservative pick: 5-6% real return. Middle: 7%. Aggressive: 8%. Use lower if you're heavy in bonds or expect lower-than-historic returns; higher is rarely justified.
Scenarios at a glance
Balance needed today to coast to a $1,500,000 FIRE number at age 65, assuming 7% real return and zero further contributions:
| Current age | Years of compounding | Balance needed today |
|---|---|---|
| 25 | 40 | ~$100,000 |
| 30 | 35 | ~$140,000 |
| 35 | 30 | ~$200,000 |
| 40 | 25 | ~$275,000 |
| 45 | 20 | ~$385,000 |
| 50 | 15 | ~$540,000 |
Every 5 years you delay roughly doubles the balance needed to coast. Compounding is the whole lever.
Worked example
Jamie is 32, wants to retire at 60, and has calculated their FIRE number (25× annual expenses of $60,000) at $1,500,000 in today's dollars. They're currently sitting on $200,000 across 401k + brokerage + Roth.
Using 7% real return:
- Years to retire: 28
- Coast number (needed today): $217,000
- Current: $200,000
- Gap: $17,000 — just a hair under coast
- Coast age (at $200,000): ≈ 61.8 → they'll hit $1.5M at age 61.8, a couple years past their 60 target
If Jamie puts another $17,000 into the portfolio over the next year (via normal 401k contributions, say), they'll be at coast. From that moment, they can choose to:
- Keep saving aggressively → retire earlier than 60
- Cut back to saving only enough to cover inflation of FIRE number → retire on schedule
- Pivot career, take a sabbatical, switch to a part-time job → retirement still happens at 60
Jamie is a year away from a much less stressful relationship with money. That's Coast FIRE.
FAQ
What's the difference between Coast FIRE and Barista FIRE?
Coast FIRE: enough invested today that no future contributions are needed; you still work to cover current expenses. Barista FIRE: partially financially independent; you take a low-stress job that covers half your expenses while investments cover the other half. Lean FIRE: reduced expenses + full retirement. Fat FIRE: same as traditional FIRE but with a larger nest egg for higher living standard.
What real return should I use?
7% is a defensible default for an 80-100% US equity portfolio over 20+ years, based on century-long historical data (~10% nominal − ~3% inflation). For more conservative portfolios (60/40 stocks/bonds), use 5-6%. For 100% bonds, use 1-2%. Underestimate on purpose; you don't want to hit 60 short of FIRE because the market was unusually weak.
Should I stop saving once I hit Coast FIRE?
You don't have to, but most people do keep saving at a reduced rate. Reasons: your expenses might grow, your FIRE number might turn out to be wrong, you might want to retire earlier than planned, or you might want a bigger margin. Stopping savings entirely is higher-variance; most Coast FIRE proponents keep saving 10-20% of income as insurance.
Does Coast FIRE assume I won't spend any of this money before retirement?
Yes — the calculation assumes the coast portfolio is fully preserved for retirement. Any withdrawal before retirement (for a home purchase, new car, emergency) pushes you back out of coast.
What if stock returns underperform historical averages?
The coast number grows — you'd need more today to reach the same target at a lower growth rate. The protection against this is (a) using a conservative return assumption, (b) keeping some contribution flowing even after coast, and (c) being flexible about retirement age if markets have a lost decade.
Is my home equity part of my coast number?
Strictly no. Coast FIRE is about invested liquid assets growing to fund retirement income. Home equity grows but doesn't produce retirement income unless you sell or reverse-mortgage. Count home equity separately as a fallback; don't include it in your invested coast number.
Last updated: April 23, 2026