The 4% rule is the most quoted number in early retirement and the most frequently misunderstood. It is not a promise, and it is not a spending limit — it is a starting withdrawal rate derived from historical 30-year outcomes.
This guide converts the rule into concrete portfolio targets across a range of spending levels, shows how the target changes with the withdrawal rate you choose, and covers the costs people routinely forget to include.
What the Rule Actually Says
The rule originates from studies of historical US market data that asked a specific question: what starting withdrawal rate, adjusted for inflation each year, would have survived every 30-year retirement window on record? The answer clustered around 4%.
Two details matter. The withdrawal is set in year one as a percentage of the portfolio, then the dollar amount rises with inflation — you do not recalculate 4% of the new balance each year. And the test was survival over 30 years, not indefinitely.
Portfolio needed = annual spending ÷ withdrawal rate
At 4% the divisor produces the familiar 25x multiple. At 3.5% it becomes 28.6x, and at 3% it becomes 33.3x.
Portfolio Targets by Spending Level
Each row shows the portfolio required to support that level of annual spending, before tax, at three withdrawal rates.
| Annual spending | At 4% (25x) | At 3.5% (28.6x) | At 3% (33.3x) |
|---|---|---|---|
| $30,000 | $750,000 | $857,000 | $1,000,000 |
| $40,000 | $1,000,000 | $1,143,000 | $1,333,000 |
| $50,000 | $1,250,000 | $1,429,000 | $1,667,000 |
| $60,000 | $1,500,000 | $1,714,000 | $2,000,000 |
| $80,000 | $2,000,000 | $2,286,000 | $2,667,000 |
| $100,000 | $2,500,000 | $2,857,000 | $3,333,000 |
| $120,000 | $3,000,000 | $3,429,000 | $4,000,000 |
The gap between columns is the price of caution. Moving from 4% to 3.5% raises the target by about 14%, which for a household spending $60,000 is roughly $214,000 — often two to three extra years of accumulation. Whether that is worth paying depends mostly on how long the retirement is expected to last.
Enter your own spending, savings rate and current balance in the FIRE retirement calculator to see both the target and the estimated date you reach it.
The Spending Figure People Get Wrong
Every number above depends entirely on the spending figure you feed in, and that is where most plans go astray. Current take-home spending is not the right input. Build the figure from what retirement will actually cost:
- Income tax on withdrawals. Money drawn from pre-tax accounts is taxable. If you need $60,000 to spend and expect an effective 12% rate, the withdrawal is nearer $68,000 and the target rises by $200,000 at 4%.
- Health insurance. For anyone retiring before state or employer coverage begins, this is frequently the single largest new line item.
- Irregular capital costs. Car replacement, a roof, appliances and major travel average out to a meaningful annual figure even though they arrive unevenly. Adding an annualised allowance is more honest than ignoring them.
- Subtract what disappears. Commuting, retirement contributions, mortgage payments that end mid-retirement and work-related costs all fall away.
Adjusting for a longer horizon
A retirement starting at 40 may run 50 years rather than 30, which gives poor sequences of returns more time to cause permanent damage. Many planners use 3.25-3.5% for horizons beyond 40 years. Others keep 4% but plan explicit flexibility: a spending floor they will never cut below, and a discretionary layer of perhaps 15-20% that pauses after a bad year.
Choosing Your Own Withdrawal Rate
The 4% figure came from testing 30-year retirements. If you plan to stop work at 45, your portfolio may need to last 50 years, and the failure rate at 4% rises materially over that horizon. Most long-horizon planners settle between 3% and 3.5%, which raises the target multiple from 25 times spending to between 28 and 33 times.
Three factors should push your personal rate down: an early retirement date, a portfolio concentrated in a single national market, and fixed costs that cannot be reduced in a bad year. Three factors allow a higher rate: a state or workplace pension arriving later, meaningful spending flexibility, and a willingness to earn part-time income during downturns.
Flexibility is worth more than precision. A retiree who can cut spending 10% in poor years supports a starting rate roughly half a point higher than one whose budget is entirely fixed. Building discretionary spending into the plan — travel, upgrades, gifts — creates that adjustment room without threatening essentials.
Whatever rate you choose, recalculate annually against the current portfolio value rather than treating the original number as permanent. The rule is a planning tool, not a contract, and the retirees whose money lasts are the ones who keep checking.