4% Rule Calculator
Enter the portfolio, expected return, inflation and the period to fund.
Income under the 4% rule
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Enter values above
Income under the 3% rule
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Income under the 5% rule
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Highest rate that lasts
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Years the 4% rule funds
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Monthly income under 4%
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Worked example
With the default inputs shown below, this calculator returns the following results:
| Input | Value |
|---|---|
| Portfolio value ($) | 800000 |
| Expected return (%) | 5 |
| Inflation rate (%) | 2.5 |
| Years to fund | 30 |
| Result | Value |
|---|---|
| Income under the 4% rule | $32,000 |
| Income under the 3% rule | $24,000 |
| Income under the 5% rule | $40,000 |
| Highest rate that lasts | 4.90% |
| Years the 4% rule funds | 41 years |
| Monthly income under 4% | $2,667 |
Values shown are produced by this page in your browser; change any input to update them.
How to use the 4% Rule Calculator
- Portfolio value ($) — default 800000
- Expected return (%) — default 5
- Inflation rate (%) — default 2.5
- Years to fund — default 30
- Press Calculate to update the results instantly.
Frequently asked questions
It comes from the Trinity study, which tested historical US market data and found that a 4% initial withdrawal, increased with inflation, survived 30 years in almost every period tested.
With lower expected returns than the historical sample, many researchers now suggest 3.3–3.5% for a 30-year horizon. The calculator’s “highest rate that lasts” shows what your own assumptions support.
It assumes a fixed inflation-linked withdrawal. In practice, cutting withdrawals after bad years raises the sustainable rate substantially — a flexible 5% can be safer than a rigid 4%.