Coast FIRE is the version of FIRE that doesn't require quitting your job, moving to Thailand, or saving 70% of your income. It's the math problem that says: if I have X dollars invested by age Y, compound growth alone will fund a normal retirement at 65 — even if I never invest another dollar.
This guide explains the math, walks through coast numbers by age, and covers when Coast FIRE actually beats traditional FIRE.
What changed in 2026
- Long-term real return assumptions softened to 5.5%–6.5% in most planning tools, down from the 7% used historically.
- Coast FIRE communities (Reddit, Bogleheads forums) doubled in 2024–2025 as more people opted for "good enough" over "leave the workforce."
- HSA-funded healthcare bridges are more common now that HSA limits hit $4,400 individual / $8,750 family in 2026.
The Coast FIRE formula
Future Value Needed at 65 / (1 + real return rate) ^ (years until 65) = Coast FIRE Number
Example: A 30-year-old who wants $1.5M (in today's dollars) at 65, assuming a 6% real return:
$1,500,000 / (1.06^35) = $195,170
That's roughly $195K invested today, never another contribution, and the math gets you to $1.5M at 65. After hitting that number, you only need to earn enough to cover current expenses.
How to calculate yours
- Step 1: Pick a target retirement number (typically 25x your projected retirement spending).
- Step 2: Pick a real return assumption (5%–7% is reasonable).
- Step 3: Calculate years until age 65 (or your target retirement age).
- Step 4: Divide target by (1 + return)^years.
- Step 5: That's your coast number. If your invested assets exceed it, you're coasting.
1. The young coaster — best at age 25–32
A 28-year-old needs roughly $150K invested to hit $1.25M at 65 (assuming 6% real). Saving aggressively for 5–7 years out of college, then easing off, beats steady saving for 35.
The trade-off: requires aggressive saving early, when income is usually lowest. Doable in tech and finance; harder elsewhere.
2. The mid-career coaster — best at age 35–45
A 40-year-old needs about $390K to hit $1.25M at 65. More common path: aggressive accumulation through 30s, declare coast at 40, downshift to part-time, lower-stress, or passion-project work.
The catch: still requires real money invested. Coast at 40 with $200K isn't coast — it's hope.
3. The Barista FIRE variant — best with healthcare needs
Coast plus a part-time job specifically for healthcare and pocket money. Trader Joe's, Starbucks, and REI famously offer benefits for ~25 hour/week work. Bridges to Medicare without ACA chaos.
The catch: depends on employer benefits policies, which can change.
Comparison: Coast FIRE numbers by age (target $1.25M at 65, 6% real)
| Age |
Coast number needed today |
| 25 |
$116K |
| 30 |
$156K |
| 35 |
$208K |
| 40 |
$279K |
| 45 |
$373K |
| 50 |
$500K |
Common mistakes to avoid
Assuming inflation-adjusted returns are 8%. Long-term real returns are closer to 5.5%–6.5%. Using 8% under-counts your coast number.
Ignoring sequence risk on the down years. A 30% drop in year 5 of coasting can blow up the math. Don't go to 100% stocks at 60 just because you're coasting.
Coasting before you actually hit the number. "I have $180K and I'll hit $200K eventually" is not coasting. It's hoping.
FAQ
What if I want to retire before 65?
Then your coast number is bigger and requires earning enough to cover expenses for longer. Coast FIRE assumes you keep working until traditional retirement age.
Does Coast FIRE work for high spenders?
Yes, but the target retirement number scales with spending. $200K/year retirement requires $5M, which means a much larger coast number.
Is Coast FIRE the same as Lean FIRE?
No. Lean FIRE means retiring fully on a small portfolio. Coast FIRE means continuing to work to cover expenses, with retirement savings on autopilot.
Where to go next
For related guides see The FIRE movement in 2026, How to invest $1,000 in 2026, and Best Roth IRA accounts 2026.