No. 04 — Milestones
Financial independence
Financial independence is the point where your portfolio's earnings cover your living costs — work becomes optional. One million dollars is the classic benchmark because of one simple piece of arithmetic: the 4% rule.
The 4% rule in plain terms
Research on historical US markets (the "Trinity study" line of work) found that withdrawing 4% of a diversified portfolio in year one, then adjusting for inflation, survived essentially every historical 30-year retirement. By that rule, $1,000,000 supports about $40,000 a year, indefinitely adjusted for inflation. Flip it around and you get the master formula: your FI number = annual spending × 25. Spend $60k, need $1.5M; spend $32k, need $800k. Your spending, not your income, sets the finish line.
Your savings rate is your retirement date
Because spending less does double duty — more invested and a smaller target — the years to independence depend almost entirely on savings rate, from any starting income:
| Savings rate | Approx. working years to FI |
|---|---|
| 10% | ~51 |
| 20% | ~37 |
| 30% | ~28 |
| 40% | ~22 |
| 50% | ~17 |
| 65% | ~10–11 |
(Assumes ~5% real returns and 4% withdrawals, starting from zero.) The jump from 10% to 20% buys back fourteen years of your life — the practical levers are in savings rate and increase your income.
Honest caveats on the 4% rule
It's a planning benchmark, not a law. Retirements longer than 30 years, high fees, or a brutal market crash in the first few years (sequence-of-returns risk) argue for 3.25–3.75% withdrawals or some flexibility — trimming spending in bad years dramatically improves survival. Healthcare before Medicare eligibility deserves its own line item. None of this changes the core math; it adds a margin of safety to it.
Flavors of the goal
Coast FI: save hard early until compounding alone will finish the job by 65, then only cover expenses. Barista FI: part-time income bridges the gap, slashing the portfolio you need. Full FIRE: the complete 25× target. Each is a different trade of working years for freedom years — put your own numbers into the millionaire calculator and the map from how to make a million dollars gets you moving.