The 4% Rule, calculated both directions
Enter your retirement expenses to find the portfolio you need — or enter your portfolio to see what you can safely withdraw. Toggle between 3.0% and 5.0% withdrawal rates to see how the assumption changes everything.
$5,000/month
Withdrawal-rate sensitivity
The same expense level produces very different requirements at different SWRs:
| SWR | Portfolio needed | Multiplier |
|---|---|---|
| 3.0% | $2,000,000 | 33.3× expenses |
| 3.5% | $1,714,286 | 28.6× expenses |
| 4.0% | $1,500,000 | 25.0× expenses |
| 4.5% | $1,333,333 | 22.2× expenses |
| 5.0% | $1,200,000 | 20.0× expenses |
The Trinity Study, in one paragraph
The Trinity Study (1998) is the common name for "Retirement Savings: Choosing a Withdrawal Rate That Is Sustainable," published in the AAII Journal by Philip L. Cooley, Carl M. Hubbard, and Daniel T. Walz — three finance professors at Trinity University in San Antonio, Texas. The study tested fixed-percentage withdrawal rates against historical US stock and bond returns from 1926 onward. Its central finding: a 4% initial withdrawal, adjusted annually for inflation, survived a 30-year retirement in 95%+ of historical periods when the portfolio held a stock-heavy mix. That single number became the "4% rule" that anchors most modern FIRE math — including this calculator.
Why the SWR slider matters
Modern research (Pfau 2020, Morningstar 2023+) argues forward-looking real returns are likely lower than the historical 1926-1998 average. That has pushed many practitioners toward a 3.3%-3.8% safe withdrawal rate for new retirees, especially those planning 40+ year retirements. On the other hand, retirees willing to flex spending downward in bear markets (dynamic withdrawal) historically support 4.5%+ safely. There is no single "right" SWR — the slider above lets you see the trade-off directly.