CoastFIRE: When Your Money Can Work for Itself
CoastFIRE is the milestone where you've invested enough that — even if you never contribute another dollar — compound growth alone will carry your portfolio to your full FIRE number by traditional retirement age (typically 65).
Once you hit it, you only need to earn enough to cover your current living expenses. The heavy lifting is done.
The Core Idea
Most retirement planning assumes you'll keep contributing throughout your career. CoastFIRE flips that assumption. It says: at some point, your existing portfolio is large enough that time and compound growth finish the job without your help.
The math depends on three things:
- Your target FI number (annual spending × 25)
- Your expected annual return (typically 7% real, inflation-adjusted)
- How many years until you want to reach full FI
Coast Number = FI Number ÷ (1 + annual return)^years
If your FI number is $1,500,000, you expect 7% real returns, and you have 25 years until you want to retire:
$1,500,000 ÷ (1.07)^25 ≈ $275,000
Invest $275,000 today, stop contributing, and in 25 years you'll have $1,500,000 in today's dollars. You've coasted.
Why It Matters
CoastFIRE is liberating because it expands what "good enough" looks like for your job.
Before reaching CoastFIRE, you need income that covers expenses and contributions. After CoastFIRE, you only need income that covers expenses — any job that pays the bills qualifies.
That opens the door to:
- Taking a lower-paying job you find more meaningful
- Starting a business that might take years to become profitable
- Moving to a lower cost-of-living area
- Working part-time
- Taking extended time off
You haven't retired, but you've dramatically expanded your options.
How It Differs from Barista FIRE
Both CoastFIRE and Barista FIRE involve "not quite retired yet" — but they're different situations:
CoastFIRE means you haven't reached your full FI number yet. Your portfolio will grow to it on its own, but you're not drawing from it. You work to cover current expenses.
Barista FIRE means you have partially reached FI (or chosen a lower spending target) and are drawing from your portfolio at a low rate, supplemented by part-time work.
In CoastFIRE, your portfolio is still accumulating. In Barista FIRE, you've begun the drawdown phase.
The Power of Starting Early
CoastFIRE demonstrates why starting early matters so much. The earlier you invest, the more time compound growth has to do the work — and the smaller your Coast Number.
At a 7% real return:
| Years to traditional retirement | Coast Number for $1.5M FI target |
|---|---|
| 35 years | ~$160,000 |
| 25 years | ~$275,000 |
| 20 years | ~$390,000 |
| 15 years | ~$545,000 |
| 10 years | ~$762,000 |
A 30-year-old aiming to retire at 65 has 35 years. They'd only need ~$160,000 invested today to coast. A 45-year-old needs significantly more.
This doesn't mean starting later is hopeless — it means the math is different, and you'll need a higher savings rate or a later retirement target to compensate.
CoastFIRE in the Calculator
You can model CoastFIRE in fyrslf by setting your annual contributions to zero at some point and seeing whether your portfolio still reaches your target. If it does: you've found your Coast point.