Coast FIRE Calculator

What is Coast FIRE?

You've hit Coast FIRE when your current savings, left completely alone, will grow into a full retirement fund by the time you retire. That's the whole definition. No more required contributions, ever.

After that point you still work, but the pressure changes completely. Every paycheck just needs to cover this month's bills. The retirement accounts can sit untouched. The word "coast" is literal: from here, compounding carries you.

Traditional FIRE asks for 25× your spending as fast as possible, then full retirement. Coast FIRE asks for far less. A 30-year-old might need only $130,000 invested today to coast to a $1,000,000 retirement at 60. Same destination, much smaller ticket. That's why people call it the most achievable flavor of FIRE.

How the Coast FIRE calculator works

It starts with your full FIRE number: annual spending × 25. Then it discounts that number back to today, using your expected return over the years left until retirement.

Then it does two useful things with the answer. First, it compares the target with what you've already saved and shows the gap. Second, it projects where your current savings land at retirement age if you add nothing more. The chart plots that growth every five years, so you can watch the curve bend upward. Starting early beats saving more, and the picture makes it obvious why.

Formula

Here r is your expected annual real return and years is the time between now and retirement. Real means after inflation: expect 10% nominal returns with 3% inflation, and you use 7%.

Example

Say you're 30, want to retire at 60, plan to spend $40,000 a year, and assume 7% real returns. Your FIRE number is $40,000 × 25 = $1,000,000. Discounted over 30 years: $1,000,000 ÷ 1.07³⁰ ≈ $131,367.

Save that amount today, contribute nothing ever again, and compounding alone delivers $1,000,000 by age 60.

Now change one input. Run the same math at age 40 and the number jumps to about $258,000. Every decade you wait roughly doubles the price of coasting. Age is the input that matters most. Full stop.

How to reach Coast FIRE faster

• Front-load contributions in your 20s and 30s. A dollar invested at 25 is worth roughly $10 at 60 (at 7%). The same dollar invested at 45 is worth about $3.80. Timing beats effort.
• Keep fees low. A 1% annual fee sounds trivial, but over 30 years it can erase nearly a quarter of your final balance. Broad index funds are the default for a reason.
• Reduce your target spending. Because the FIRE number is 25× spending, trimming $5,000 a year off expected retirement spending cuts your Coast FIRE number by $125,000 before discounting. Highest-leverage input in the formula.
• Don't interrupt compounding. Pulling money out before retirement resets the clock. Keep a separate emergency fund so surprises never touch the investments.

Coast FIRE vs Barista FIRE vs Lean FIRE

People mix these three up constantly, so here are the quick definitions.

Coast FIRE: your savings grow untouched while you work a normal job to pay the bills. No career change required.

Barista FIRE: you quit the career and pick up enjoyable part-time work. A smaller portfolio covers the gap between spending and that income. Curious how small the target gets? Our Barista FIRE calculator shows the math.

Lean FIRE: fully retired on a minimalist budget, typically under $40,000 a year per household.

Of the three, Coast FIRE demands the least lifestyle surgery. No new job, no frugality contest.

Limitations to keep in mind

The math assumes smooth returns. Real markets aren't smooth. A crash early in your coasting years hurts far more than one near the end. That's sequence-of-returns risk, and no simple calculator models it.

Taxes get ignored too, which is why plenty of people run their numbers at 5–6% instead of 7%. And "annual spending in retirement" is a guess dressed up as an input. Healthcare costs love to surprise people. Revisit your number once a year and you'll be fine.

Frequently asked questions

What is the difference between FIRE and Coast FIRE?

FIRE means reaching full financial independence and retiring early. Coast FIRE means saving enough, early, that growth alone finishes the job. You keep working, but saving for retirement becomes optional instead of urgent.

What return rate should I use?

7% is the standard pick: the long-term real return of the US stock market, after inflation. Feeling cautious? Use 5%. Holding lots of bonds? Use 5% too. The conservative number keeps you honest.

Does Coast FIRE include inflation?

Yes, as long as you stay consistent. Enter spending in today's dollars and use a real return like 7%. Both sides of the equation stay in today's dollars, so inflation cancels out.

What if I haven't reached my Coast FIRE number yet?

The calculator shows your exact gap. Close it sooner rather than later. A year of compounding bought in your 30s is worth roughly double one bought in your 40s.

Can I still contribute after hitting Coast FIRE?

Of course. Extra contributions just move full retirement earlier or raise what you can spend later. Coast FIRE is a floor, not a ceiling.

Is Coast FIRE realistic without a high income?

More realistic than full FIRE, because the target is so much smaller. A 30-year-old needs roughly $130,000–$160,000 to coast toward a $40,000-a-year retirement. With a median income and an aggressive savings rate, that's 5–8 years of focused saving.

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