The savings milestone after which compounding alone funds retirement
| Coast at age… | Target needed then | You reach it… |
|---|
Coast FIRE reframes the retirement question in a way that changes careers: instead of "when can I stop working?", it asks "when can I stop saving?" — the point where your invested balance, left alone, compounds to full retirement funding by traditional retirement age. Past that milestone, work only needs to cover current living costs, which makes downshifts, sabbaticals, passion jobs and parenthood pauses financially rational decades before full independence.
The exponent is the whole story. A 30-year-old targeting $55,000/yr of retirement spending needs $1.375M at 65 — but only ~$250,000 invested today at 5% real return. At 25, it's ~$195,000. Time does 80% of the work if you give it the raw material early; the table shows how the target balloons for every five years of delay.
| Variant | Milestone | Then what |
|---|---|---|
| Coast FIRE | Compounding will finish the job | Work covers living costs only; saving optional |
| Barista FIRE | Portfolio covers part of spending | Part-time work covers the gap (and insurance) |
| Full FIRE | 25× spending, now | Work fully optional |
It's the 4% rule inverted — the standard full-retirement target. Conservative planners use 28–30× (a 3.3–3.5% withdrawal rate); the calculator's spending input lets you bake that in by adjusting either number.
Most don't — they downshift instead: capture the 401(k) match, drop the rest. The milestone's value is optionality and the license it gives for career risk, not a commandment to quit saving.
5% real (7% nominal − 2% inflation) is the standard defensible figure for stock-heavy portfolios. Run 4% as your caution case — if you're coast-complete even at 4%, the milestone is robust.
Not in the headline math — which makes it conservative: benefits arriving at 67 reduce the portfolio the 25× target actually needs. Treat Social Security as your margin of safety.
Any invested dollars compound the same; tax-advantaged accounts just compound faster after-tax. Coasters usually front-load 401(k)/IRA/HSA first for exactly that reason — see the contribution tools.
Then you're on the standard FIRE path: every extra year of saving pulls full independence closer. Coast is a milestone on that road, not an exit from it.
Yes — every figure computes locally in your browser.
Find your coast number tonight — for savers in their 20s and 30s it's startlingly close, and knowing it changes how every career decision feels. The sprint is finite; the compounding is not.