What is the 4% rule, and does it actually work?
TL;DR: The 4% rule says you can withdraw 4% of your retirement portfolio in year one, then adjust that amount for inflation every year after, with a historically low chance of running out of money over roughly a 30-year retirement. It's based on real historical market data, not an arbitrary guess — but it has real, worth-understanding limitations, especially for retirements longer than 30 years.
Where the number actually comes from
The 4% figure originates from research (commonly associated with the "Trinity Study" and related work) that tested historical U.S. market returns across many rolling 30-year periods, checking what withdrawal rate would have avoided running out of money in the worst historical periods, not just the average one. 4% held up in the vast majority of historical 30-year windows tested.
What it gets right
Unlike a simple "expected return minus inflation" calculation, the 4% rule is deliberately stress-tested against real historical bad periods (including major downturns), not just an optimistic average-case scenario — which is exactly why it's more conservative than what a naive average-return calculation would suggest is safe.
Where it genuinely breaks down
- Retirements longer than ~30 years — the original research window doesn't cover a 45-50+ year retirement, which is exactly what early retirement (FIRE) at 35-40 implies. A more conservative 3-3.5% is commonly used for this reason.
- Different markets and time periods — the original research is U.S.-market-based; other markets have different historical return and volatility profiles, and future returns are never guaranteed to resemble any historical period.
- It assumes a fairly static portfolio allocation — real retirees often adjust their withdrawal or allocation in response to market conditions, which the simplest version of the rule doesn't account for.
What to actually do with this information
Treat 4% as a reasonable, historically-grounded starting point for a traditional-length retirement — not a universal law. For a longer early-retirement horizon, or simply for extra safety margin, shifting to 3-3.5% is a common, defensible adjustment. The right number for you also depends on your flexibility to reduce spending in a bad market stretch, which the simple percentage doesn't capture at all.
See your FIRE number at different withdrawal rates
Our Retirement & FIRE Readiness Report lets you adjust the safe withdrawal rate directly and see how it changes your FIRE number and timeline — rather than locking you into 4% as the only option.
Frequently asked questions
Is the 4% rule still valid today?
It's a reasonable, historically-grounded starting point for a roughly 30-year retirement, based on real historical market stress-testing rather than a guess — but it wasn't built around retirements longer than that, and future returns are never guaranteed to resemble historical ones, so it should be treated as a starting point, not a guarantee.
What withdrawal rate should I use for early retirement?
Many early-retirement planners use 3-3.5% instead of the classic 4%, specifically because early retirement implies a longer withdrawal period (45-50+ years) than the original 4% research modelled (roughly 30 years).
Where does the 4% rule come from?
It originates from research testing historical market returns across many rolling 30-year periods to find a withdrawal rate that would have avoided running out of money even in the worst historical periods tested, not just the average case — commonly associated with the 'Trinity Study.'