The 4% rule is a retirement spending guideline: withdraw 4% of your portfolio in the first year of retirement, adjust that dollar amount for inflation each year, and historically you would not run out of money over a 30-year period.
It is one of the most cited rules in FIRE (Financial Independence, Retire Early) planning because it turns annual spending into a target portfolio size: roughly 25× annual expenses.
Where the 4% rule came from
The rule is rooted in the Trinity Study (1998) and related research that tested withdrawal rates against U.S. stock and bond returns over rolling 30-year periods. A 4% initial withdrawal with a diversified portfolio succeeded in most historical scenarios.
The study assumed annual rebalancing and did not account for fees, taxes, or changing spending needs. It is a starting point, not a promise about future markets.
Turning spending into a FI number
If you plan to spend $50,000 per year in retirement, 25× that is $1,250,000 — your rough FI target at a 4% withdrawal rate.
Lower spending means a smaller target. A more conservative 3.5% withdrawal rate implies about 28.6× expenses; a 3% rate implies 33×.
FIRE calculators use your actual expenses, savings, and return assumptions to estimate when you hit that target — not just the static 25× shortcut.
Criticisms and modern adjustments
Some planners argue 4% is aggressive for early retirees with 40–50 year horizons, or when starting retirement into expensive markets and low bond yields.
Sequence-of-returns risk matters: poor returns in the first decade of withdrawals do more damage than poor returns later. Flexible spending — cutting back in down years — improves outcomes.
Many FIRE adherents plan for 3–3.5% withdrawal rates, part-time income (Barista FIRE), or variable spending rules instead of rigid 4% inflation adjustments.
How to use it in practice
Use the 4% rule to ballpark a target, then stress-test with different rates, return assumptions, and time horizons.
Combine withdrawal rate planning with tax-aware account location (taxable, traditional, Roth) and Social Security timing if applicable.
Revisit spending and portfolio allocation as you approach and enter retirement. The rule is a framework, not a set-and-forget mandate.
Model your withdrawal plan
Enter your portfolio, annual spending, expected return, and withdrawal rate to see how long your money lasts and when you reach financial independence.
Use the FIRE calculator for FI timelines, the retirement calculator for withdrawal projections, and the FIRE comparison tool to compare Lean, Coast, and Barista paths.