You have your FI number and a rough timeline, and the timeline is longer than you hoped. FIRE is not one path: once the basic math is in hand — 25× spending, reached faster by a higher savings rate — you can scale it to fit your life and your appetite for frugality. And one variant, Coast FI, is less a destination than a milestone you may be able to hit in your 30s.
The four common flavors
The variants differ on two dials: how much you plan to spend (which sets the size of the number) and whether you stop working entirely or downshift.
| Variant | The idea | Typical FI number | Work afterwards? |
|---|---|---|---|
| Lean FIRE | A deliberately minimal lifestyle | Smaller — low spending × 25 | None planned |
| Fat FIRE | A comfortable, even generous lifestyle | Large — high spending × 25 | None planned |
| Barista FIRE | Part-time work covers some costs plus benefits | Partial — the portfolio fills the gap | Part-time, by choice |
| Coast FIRE | Invest enough early; let growth finish the job | Reached later, with no new saving | Enough to cover today's costs |
- Lean FIRE chases freedom by keeping spending low, often $25,000–$40,000 a year. The number is small and arrives sooner; the trade is a tight life with little slack, and the tradeoffs lesson is direct about how that wears on people.
- Fat FIRE keeps a roomy lifestyle — travel, a paid-off house, generous everyday spending — so the number is large. A $100,000-a-year lifestyle implies $2,500,000 at 25×. More comfort, much longer road.
- Barista FIRE is the in-between many people want: a portfolio that covers most costs, topped up by part-time work that you enjoy and that often supplies health coverage. Employer plans usually end when the job does and Medicare starts at 65, so a part-time job with benefits solves the biggest pre-65 cost, which is why the "barista" label stuck. The health insurance lesson covers what coverage costs when you have to buy it yourself.
Coast FI: the milestone hiding in plain sight
Coast FI deserves its own section because it is the variant you can realistically reach first. The idea: invest enough, early enough, that compound interest alone — with no further contributions — is on track to grow into your full FI number by a traditional retirement age. Once you hit your Coast number you can stop saving for retirement and only need your income to cover today's costs.
That is a large shift in pressure. You are not financially independent yet — you still work to pay this month's bills — but the future is handled. It works because of the most valuable ingredient in compounding: time. A dollar invested at 25 has four decades to multiply; the same dollar at 45 has two. Coast FI front-loads the hard saving into the years when each dollar is worth the most, which is exactly what the start-early lesson and the account order of operations drive at.
| Full FI | Coast FI | |
|---|---|---|
| What it requires | 25× spending, invested now | A smaller amount that grows into 25× by retirement |
| Saving after reaching it | Optional — you are free | None needed for retirement |
| What your income still covers | Nothing required | Today's living costs only |
| When it is typically reached | Later | Much earlier, sometimes in your 30s |
Every one of these numbers depends on a return that may not arrive on schedule, and the tradeoffs lesson covers what the spreadsheet leaves out. But as a framework, the flavors — Coast FI especially — turn one intimidating finish line into a series of milestones: a full emergency fund, a walk-away fund, your Coast number, and then, whenever you choose, the rest.