The amount you need today so compound interest finishes the job — no more saving required.
How much you'd spend per month in retirement, in today's money.
Total in your retirement / brokerage accounts today.
How much you invest each month right now.
Defaults match our FIRE Planner: 11% nominal return, 2.5% inflation, 4% withdrawal rate (8.5% real return based on long-run S&P 500 averages). Adjust if you want a more conservative view.
Stock market avg. ~11%
Historical avg. ~2-3%
The 4% rule is FIRE standard
51.785 $
Coast at age 34 (around —)
After that, you never need to invest another dollar toward retirement.
Your full FIRE target is 900.000 $
Want to track this for real? See your actual progress against this milestone month-over-month.
Start tracking| FIRE flavor | Annual spend | FIRE target | Coast today |
|---|---|---|---|
Lean FIRE 0.7× your monthly expenses | 25.200 $ | 630.000 $ | 36.249 $ |
Coast FIRE Your monthly expenses (this calculator) | 36.000 $ | 900.000 $ | 51.785 $ |
Barista FIRE Half from portfolio, half from part-time work | 36.000 $ | 450.000 $ | 25.892 $ |
Regular FIRE Your monthly expenses, full coverage | 36.000 $ | 900.000 $ | 51.785 $ |
Fat FIRE 1.5× your monthly expenses | 54.000 $ | 1.350.000 $ | 77.677 $ |
Updated May 2026
Coast FIRE is the moment you can stop investing for retirement and still retire on time. You've invested enough early in life that compound interest alone carries the portfolio to your full FIRE number — usually by age 65.
The trick is doing the math backwards. Pick your full FIRE number (annual expenses × 25). Then ask: how much would I need invested today so that, growing at the historical real return, it reaches that number by retirement age? That's your Coast FIRE number. Once you hit it, you can switch jobs, go part-time, take a sabbatical, or just stop contributing — your retirement is on autopilot. Read the full Coast FIRE explainer →
Coast FIRE math is four equations stacked together. Every Coast FIRE calculator on the internet uses these — we just put yours in front:
1. Your full FIRE target
FIRE Target = Annual Expenses ÷ Withdrawal Rate
Example: $3,500/month → $42,000/year ÷ 4% = $1,050,000
2. Your Coast FIRE number
Coast FIRE = FIRE Target ÷ (1 + Real Return)^Years to Retirement
Example: $1,050,000 ÷ (1.085)^35 = ~$60,000 needed today at age 30
3. Your retirement income
Annual Withdrawal = Total Savings × Withdrawal Rate
Example: $1,050,000 × 4% = $42,000/year
4. Monthly income at retirement
Monthly Income = (Total Savings × Withdrawal Rate) ÷ 12
Example: ($1,050,000 × 4%) ÷ 12 = $3,500/month
| Your age | Years to 65 | At your expenses | At 1.5× your expenses |
|---|---|---|---|
| 20 | 45 | 22.904 $ | 34.355 $ |
| 25 | 40 | 34.439 $ | 51.659 $ |
| 30 | 35 | 51.785 $ | 77.677 $ |
| 35 | 30 | 77.866 $ | 116.800 $ |
| 40 | 25 | 117.084 $ | 175.627 $ |
| 45 | 20 | 176.055 $ | 264.082 $ |
| 50 | 15 | 264.726 $ | 397.089 $ |
Assumes 8.5% real return (11% nominal − 2.5% inflation), 4% safe withdrawal rate. Today's purchasing power.
Coast FIRE isn't a finish line — it's a release valve. Here's how it compares to the other flavors:
Three steps and one optional tweak:
Enter your age and the age you want to retire. Default 65.
Enter how much you'd spend per month in retirement — in today's money.
Enter what you've already invested. The calculator shows your Coast FIRE number and the age you can stop contributing.
Open Advanced assumptions to override the 11% return / 2.5% inflation / 4% withdrawal defaults.
The earlier you reach Coast FIRE, the more options you buy. Seven things that move the needle:
Front-load contributions in your 20s and early 30s — every $1,000 invested at 25 is worth ~$15,000 at 65 (8.5% real).
Use tax-advantaged accounts first (401(k) match, Roth IRA, HSA) — compounding tax-free supercharges the Coast date.
Index funds, not stock picks — Coast FIRE math assumes broad-market returns. Concentrated bets distort the numbers in both directions.
Recalculate yearly — lifestyle creep raises your FIRE target, which raises your Coast number.
Keep an emergency fund — Coast FIRE doesn't mean stop earning. You still need 3-6 months of expenses outside the portfolio.
After Coast FIRE, keep contributing if you can — the floor becomes a buffer against down markets.
Don't quit the day after you hit Coast — give the portfolio at least a year above the line to confirm you weren't surfing a bull market.
Coast FIRE is the moment you have enough invested that compound interest alone — with no more contributions — will grow to your full FIRE number by retirement age. You can still work to cover monthly expenses, but you no longer need to save for retirement. It's the floor, not the ceiling.
Two steps. First, find your full FIRE number: annual expenses ÷ withdrawal rate (usually 4%). Then divide by (1 + real return)^(years until retirement). At our default 8.5% real return and 35 years to 65, a $1.05M FIRE number means you need about $60,000 invested today.
Coast FIRE = FIRE Target ÷ (1 + Real Return)^Years to Retirement. Where FIRE Target = Annual Expenses ÷ Withdrawal Rate, and Real Return = Nominal Return − Inflation. This calculator runs all of that for you.
Roughly 6% of your full FIRE number, if you're retiring at 65 and using our default 8.5% real return. For $1.05M FIRE (covers $3,500/month in expenses), that's about $60,000 invested today. Use the calculator above for your exact numbers.
Coast FIRE means your portfolio will reach FIRE on its own — you still earn enough to cover today's bills but can stop contributing. Barista FIRE means your portfolio doesn't quite cover full retirement yet, so you keep a part-time job indefinitely whose income closes the gap. Coast is upstream of Barista.
Lean / Regular / Fat FIRE describe the size of the finish line (low spend, mid spend, luxury spend). Coast FIRE describes a milestone on the way — you can have Lean Coast FIRE, Regular Coast FIRE, or Fat Coast FIRE depending on your monthly expenses. Coast and the others aren't competing — they answer different questions.
Absolutely — many people do. Coast FIRE is permission to stop, not a mandate. Common patterns: keep the 401(k) match (it's free money), drop discretionary contributions and redirect them to lifestyle/sabbaticals/business, or keep contributing at full pace and reach full FIRE 5-10 years sooner.
We default to 11% nominal − 2.5% inflation = 8.5% real return, based on long-run S&P 500 averages. Many calculators use 7% real (more conservative). Both are defensible. Open Advanced assumptions and try both — if your Coast date doesn't change by more than 2-3 years, the assumption isn't the limiting factor; your contribution rate is.
Yes. Every number you enter and every number we show is in today's purchasing power. We compute compound growth at the real (inflation-adjusted) rate, so the FIRE target you see is the spending power you'll actually have — not a nominal number 35 years from now that buys half as much.
Yes, if you start early. A 25-year-old who saves $850/month for ~6 years reaches Coast FIRE for a $1M target. The math gets harder the later you start — every 5 years of delay roughly doubles the required Coast number. But late is still better than never.
Your portfolio drops, so the formula now says you owe more contributions to get back to the Coast line. The good news: Coast FIRE assumes 30-40 year horizons, and the U.S. stock market has never had a 20-year period with negative real returns. Most people who hit Coast FIRE and then see a 30% drawdown resume contributions for a year or two and get back on track.
4% is the original Trinity Study guideline and still the most common default — gives a 95% historical success rate over 30 years. 3.5% is the more conservative modern guideline (Bengen and others, for early retirees with 40-50 year horizons). Lower withdrawal rate = larger FIRE target = larger Coast FIRE number. Open Advanced assumptions and try 3.5% to see the impact.
This number assumes perfectly steady contributions. Reality isn't. Track whether you're ahead of plan — with your real accounts.
Track your real net worthThis calculator is for educational use. Past returns don't predict future returns. Talk to a licensed financial advisor before making investment decisions, and treat any single 'number' (FIRE, Coast FIRE, Barista FIRE) as a guideline, not a guarantee.
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