This is the textbook 25× FIRE number, and it genuinely works, at about $53,000 to $55,000 a year all-in rather than the advertised $60,000. Here's the backtested math for a retirement that has to last half a century.
A million and a half at 45 is the textbook FIRE finish line: 25 times a $60,000 lifestyle, right on the rule-of-25 target. The catch is that the rule was calibrated for a 30-year retirement, and yours might need to run 45 or 50. I built a calculator that backtests exactly this, every historical starting year, real federal and state taxes, so here's what the textbook case actually looks like when you run it honestly.
| Where the money sits | At a 4% rate | At 3.5% |
|---|---|---|
| All of it in a taxable brokerage | $55,250/yr | $48,250/yr |
| $850,000 in a 401k, rest taxable, Roth ladder running | $53,250/yr | $47,000/yr |
Maximum all-in spending, including $8,000/yr for health insurance. Single filer, a flat ~5% state tax, 7% real return. Every figure links to the live calculation, so you can change any assumption.
The all-in sustainable number is about $55,250 a year at the classic 4% rate, or $48,250 at the 3.5% I'd genuinely use for a half-century horizon. The $60,000 the rule of 25 promised? After taxes and an $8,000 health plan it needs roughly $1,638,474 of portfolio, which your $1.5 million becomes by about age 47.0 without another dollar saved. Two years of patience, or about $140k of gap. Annoying, not fatal.
This is the page where the withdrawal-rate fine print matters most. Bengen's 4% and the Trinity Study both tested 30-year windows; retire at 45 and you're asking the same portfolio to survive a window two-thirds longer, with that many more chances to begin in a year like 1966 or 1973. Longer horizons are why the FIRE community drifts toward 3 to 3.5%, and why my default is 3.5% with a cash buffer. I wrote up the full reasoning, including what later reassessments of Bengen's own work found, on the safe withdrawal rate page. The practical version: at 3.5% against a 7% real return the portfolio tends to keep growing while paying you, which is a different and sturdier goal than merely not dying broke.
At 45 the 59½ wall is a fourteen-year problem. With $850,000 of this portfolio in a 401k, your bridge is the taxable $575,000 plus $75,000 cash, and the Roth conversion ladder does the heavy lifting: convert a slice annually, wait five tax years, withdraw penalty-free, repeat. In the table above the ladder scenario gives up only a couple thousand a year versus all-taxable, which surprised me the first time I modeled it. The ladder is cheap. Running out of bridge money before the first conversions season is the actual failure mode, and with five-plus years of accessible spending here, you're clear.
Medicare is at 65, so this plan buys its own coverage for two decades. I budgeted $8,000 a year here, and the number that actually matters for your premium is your taxable income, not your spending: living off brokerage sales, much of each withdrawal is your own basis coming back, which can keep reported income low enough for meaningful ACA subsidies. The enhanced pandemic-era subsidies expired at the end of 2025, though, and the 400%-of-poverty-line cliff is back for 2026, so the conversion ladder and the subsidy math now fight over the same income space. Details on health insurance before 65.
See this exact scenario live, then make it yoursVariants: no state income tax · California · or change anything once it loads.
Not financial advice. Consult a fee-only fiduciary CFP for personalized guidance. Tax figures use 2026 brackets.