4% Rule Calculator

What the 4% Rule Actually Says

The 4% rule is a heuristic for how much a retired person can withdraw from their portfolio annually without depleting the principal across a typical 30-year retirement. A 1,000,000 portfolio supports 40,000 of annual spending at 4%. The rule assumes a balanced portfolio (typically 60% stocks and 40% bonds), annual withdrawals adjusted upward for inflation, and a 30-year retirement horizon. Historical analysis shows this rate rarely failed across the worst market sequences, which is why it became the default planning number. The calculator applies the rate directly to any portfolio size.

Where the Rule Originated

The 4% rule emerged from the work of William Bengen in the 1990s and was refined by the Trinity Study (Cooley, Hubbard, Walz). Researchers tested various withdrawal rates against historical market data to find rates that survived the worst 30-year sequences. The 4% rate succeeded in nearly all scenarios; 5% failed in several; 3% succeeded in all historical cases with substantial margin. The 4% figure became the widely adopted default because it balanced sustainability with reasonable spending capacity.

Why the Rule Is a Starting Point, Not a Guarantee

Past performance does not guarantee future results — the 4% rule describes historical outcomes, not future ones. Current low bond yields and elevated stock valuations have led some researchers to suggest 3-3.5% may be safer for new retirees today. Longer retirements (40-50 years for early retirees) need lower rates. Shorter retirements can higher rates reflect. Flexible withdrawal strategies (adjusting downward in bad years) typically sustain higher average rates. The calculator lets you model different rates directly — the specific rate depends on personal circumstances.

Worked Example for a Typical Retirement

Portfolio value 1,000,000. Withdrawal rate 4%. Annual withdrawal: 40,000. Monthly: 3,333.33. Weekly: 769.23. Daily: 109.59. The portfolio supports 40,000 annual spending indefinitely under the rule's assumptions. Scale portfolio to 2,500,000: annual withdrawal climbs to 100,000 — comfortable upper-middle-class retirement. Drop to 500,000: annual withdrawal is 20,000 — requires substantial supplementation from social security, pension, or continued earnings.

Why Monthly Figures Matter More Than Annual

Retirement expenses happen monthly, not annually. A 4% annual withdrawal on a 1,000,000 portfolio works out to 3,333 monthly — directly comparable to the current monthly budget. If current expenses run 5,000 monthly, the portfolio is undersized for the target spending. If current expenses run 2,500 monthly, the portfolio supports that spending with meaningful buffer. The calculator returns monthly, weekly, and daily equivalents so the comparison is direct rather than requiring mental conversion.

Variable Withdrawal Strategies

The basic 4% rule assumes fixed annual withdrawals adjusted only for inflation. More sophisticated strategies adjust withdrawals based on market performance. Guardrails approach (reduce spending by 10-15% when portfolio drops significantly; increase when portfolio grows). Flexible spending (cut discretionary spending in down years). Floor-and-ceiling (establish minimum acceptable spending and maximum spending ceiling). These variable strategies typically sustain higher average withdrawal rates than the fixed rule, often 4.5-5% annual equivalent, at the cost of spending variability year-to-year.

How the Rule Handles Sequence of Returns Risk

A portfolio that experiences poor returns in the first 5-10 years of retirement faces sequence of returns risk — early depletion that cannot recover even with subsequent strong markets. The 4% rule historically survived worst-case sequences because 4% is conservative enough to weather early bad years. Higher withdrawal rates (5-6%) are more vulnerable to sequence risk. One practical mitigation: hold 1-2 years of expenses in cash or short-term bonds at retirement start, so the portfolio does not need to be sold into a down market for immediate spending.

What the Calculator Does Not Model

Inflation adjustment over time (the rule assumes annual inflation adjustments; actual annual withdrawal amounts grow year-over-year). Tax treatment of withdrawals, which varies significantly by account type (traditional retirement accounts, tax-advantaged, taxable). Required minimum distributions from certain retirement account types at specific ages. Social security, pensions, or other non-portfolio income. Unexpected large expenses like long-term care. Market volatility that changes portfolio value and theoretical withdrawal amount year-over-year. The calculator provides the simple starting figure; comprehensive retirement planning layers in these complications.

When to Consider Higher or Lower Rates

Lower than 4% (3-3.5%) when: retirement horizon exceeds 30 years, current market valuations are elevated, conservative personal preference, significant legacy goals. Higher than 4% (4.5-5%) when: retirement horizon is under 20 years, substantial non-portfolio income covers baseline expenses, flexible spending strategy in place, willing to reduce spending in bad years. The calculator is a tool for modelling; the specific rate is a personal planning decision informed by individual circumstances.

Common 4% Rule Mistakes

Treating 4% as certain rather than historical probability. Applying to retirement horizons far different from the 30-year basis. Using with portfolio allocations far from 60/40 stocks/bonds. Forgetting that the 4% applies to initial portfolio value — subsequent annual withdrawals are inflation-adjusted rather than 4% of current portfolio. Ignoring the sequence of returns risk in early retirement years. Not factoring in non-portfolio income that reduces the portfolio withdrawal need. The calculator provides the baseline math; interpreting it correctly requires understanding the rule's assumptions and limitations.