Glossary · Definition
4% rule
The 4% rule says you can withdraw 4% of your starting retirement balance annually (adjusted for inflation), and your portfolio will likely last 30 years. Origin: William Bengen 1994. Modern refinements: 3.0-3.5% for longer retirements or volatile markets.
Definition
The 4% rule says you can withdraw 4% of your starting retirement balance annually (adjusted for inflation), and your portfolio will likely last 30 years. Origin: William Bengen 1994. Modern refinements: 3.0-3.5% for longer retirements or volatile markets.
What it means
Bengen’s original analysis used historical US returns 1926-1992, 60/40 stock/bond portfolio, and a 30-year retirement. He found that 4% initial withdrawal (then inflation-adjusted annually) survived all historical periods. The Trinity Study (1998) refined and confirmed. Modern challenges: longer retirements (early retirees plan for 40-50 years), elevated current valuations (low expected stock returns), and sequence-of-returns risk (bad years early are devastating). Refinements: dynamic spending rules (spend more in good years, less in bad), variable percentage withdrawal (always withdraw same %), guardrails (Guyton-Klinger). Conservative researchers now suggest 3.0-3.5% for early retirement.
Advertisement
Formula
safe_withdrawal_year_1 = portfolio_balance × 0.04. Subsequent years: previous_withdrawal × (1 + inflation)
Why it matters
The 4% rule is the most-cited retirement-planning shortcut and the basis of the “25x annual expenses” FIRE target. But blind application can produce poverty for early retirees in bad-luck markets. For typical 65-year-old retirees with normal life expectancy, 4% is reasonable. For 50-year-old early retirees: drop to 3.0-3.5%. For anyone using it: have a plan for adjusting downward in bad-market years (the rule’s “rigid” spending pattern is what fails; flexible spenders almost always succeed).
Example
$1.5M retirement portfolio. Year 1 withdrawal: $60K. Year 2 (3% inflation): $61.8K. Year 3: $63.7K. The dollar amount adjusts for inflation; the percentage of remaining balance fluctuates. Bengen showed historically this lasted 30+ years across all starting periods.
Related free tools
Frequently asked questions
Is 4% still safe?
For 30-year retirements with diversified portfolios: yes, with 95%+ historical success rate. For 40+ year retirements (early retirees): drop to 3.0-3.5% for similar safety.
What about Social Security?
Most planners back out SS as guaranteed income. Need 25x of (annual spending - SS benefit), not 25x of total spending. Reduces required portfolio significantly.
What if my portfolio crashes?
Sequence-of-returns risk. The 4% rule’s ‘rigid spending’ pattern is what fails — flexible spenders who reduce withdrawals 10-20% in down markets almost always succeed even with bad sequences.
Related terms
- DefinitionNominal vs real returnsNominal return is the headline number (‘your fund returned 10% this year’). Real return is what’s left after inflation (10% nominal − 3% inflation = 7% real). For long-term planning, real returns are the only number that matters because purchasing power, not dollars, is what funds your retirement.
- DefinitionCompound interestCompound interest is interest earned on both your original money AND the interest it's already earned. Over long periods, this 'interest on interest' effect is what turns modest monthly contributions into retirement-level balances.
- DefinitionFIRE (Financial Independence Retire Early)FIRE (Financial Independence Retire Early) is a movement built around aggressive saving (50-70% of income) and investment to reach financial independence — often by age 40-50, sometimes earlier.