The Core Difference
Coast FIRE and full FIRE are the same destination — financial independence — arrived at by different routes with different intermediate milestones.
In coastfire, you invest enough early that compound interest does the rest. You continue working, but only to pay current living expenses — your retirement is already funded and growing independently. The coastfire milestone typically arrives 8–15 years before full FIRE for the same household.
In full FIRE, you accumulate the complete 25× your annual spending before leaving work entirely. No earned income is required after that point. The larger portfolio, the longer accumulation period, but the complete freedom at the end.
Full FIRE: Your invested portfolio alone = covers all living expenses permanently. No work required at any point.
Side-by-Side Comparison
| Feature | Coast FIRE (Coastfire) | Full FIRE |
|---|---|---|
| Continue working after milestone? | Yes — to cover current expenses | No — completely optional |
| Portfolio required at milestone | Fraction of full FIRE number | Full 25× annual spending |
| Typical time to reach (25-year-old) | 5–12 years of disciplined saving | 15–25+ years |
| Psychological relief | Immediate at coastfire milestone | Complete at full FIRE date |
| Career flexibility gained | Significant — can take pay cuts, change careers | Complete — no income needed |
| Healthcare risk (US) | Lower — employer coverage likely | Higher — decades before Medicare |
| Sequence-of-returns risk | Lower — earned income provides buffer | Higher — portfolio is sole income source |
| Required savings rate | High early, then optional/reduced | Consistently high (30–60%) |
| Suitable for those who value work | Yes — work continues by choice | Only if full exit is the goal |
Portfolio Size at Each Milestone
At $50,000/year annual retirement spending (FIRE number = $1,250,000) and 7% real return:
| Age | Coast Fire Number (Retire 65) | Full FIRE Number | Difference |
|---|---|---|---|
| 25 | ~$117,000 | $1,250,000 | Coastfire is 91% smaller |
| 30 | ~$164,000 | $1,250,000 | Coastfire is 87% smaller |
| 35 | ~$230,000 | $1,250,000 | Coastfire is 82% smaller |
| 40 | ~$322,000 | $1,250,000 | Coastfire is 74% smaller |
The coast fire number is dramatically smaller than the full FIRE number — which is why the coastfire milestone is achievable years earlier, even with the same savings rate. Use the free coastfire calculator to find your specific number at your current age.
Who Chooses Each Path
Coast FIRE suits people who:
- Enjoy their work — or enjoy some version of it — and want flexibility rather than full exit
- Want the earliest possible meaningful financial milestone rather than waiting 15–20 more years for full FIRE
- Have family or healthcare commitments that make employer-linked benefits important
- Find the 40–60% savings rate required for aggressive full FIRE unsustainable long-term
- Are early in their career (25–35) where the coastfire number is smallest and most achievable quickly
Full FIRE suits people who:
- Have a clear, compelling vision of what post-work life looks like and genuinely want to stop working
- Can sustain a high savings rate (30–60%) for an extended period without burning out
- Have high income that makes aggressive saving feasible without significant lifestyle sacrifice
- Want complete financial independence — not just retirement security — as the primary goal
The Combined Strategy: Coast First, Then Full FIRE
The most common real-world path is not a binary choice between coastfire and full FIRE — it's using coastfire as the first milestone on a longer journey toward full financial independence. Once you reach your coast fire number, the mandatory savings pressure lifts. Many people continue investing at a reduced rate and find themselves reaching full FIRE earlier than they expected, simply because their portfolio has been compounding steadily throughout.
Use the coast fire retirement calculator to see both milestones at once: the coast fire number (your first goal) and the full FIRE number (your eventual destination). The coast fire chart shows exactly when both are crossed at your current contribution rate.