Project how long your retirement portfolio lasts under a fixed withdrawal rate, with returns and inflation.
Years portfolio lasts
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Year 1 withdrawal
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Ending balance at horizon
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Your breakdown
Updates live as you type| End of year | Balance after $60,000 draw and 3% growth |
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Spending a fixed dollar amount, adjusted for inflation
The first thing to understand about the 4 percent rule, and about this calculator, is what gets withdrawn. You do not take 4 percent of whatever the balance happens to be each year. You take 4 percent of the starting balance in year one, fix that dollar amount, and then keep spending that same purchasing power every year afterward. Because you enter a real (inflation-adjusted) return, the tool holds the year-one withdrawal constant in today's dollars and lets the portfolio rise or fall around it. A balance that earns more than you pull out grows; one that earns less shrinks until it is gone. That fixed-dollar mechanic is the whole point, and it is what makes a retirement vulnerable when the math turns against it.
When 6 percent drains a million-dollar portfolio
Set the inputs to a $1,000,000 portfolio, a 6 percent initial withdrawal rate, a 3 percent real return, and a 30-year horizon. Year one you withdraw $60,000. Every year after, you take that same $60,000 while the surviving balance grows 3 percent. Watch how the gap between a 6 percent draw and a 3 percent return erodes the principal.
The portfolio lasts 22 years and dies eight years short of a 30-year plan. A 6 percent fixed withdrawal simply outruns a 3 percent real return. Drop the withdrawal to 5 percent and the same portfolio stretches to 29 years; drop it to 4 percent and it survives the full horizon with room to spare. The decline is gentle at first, then accelerates, which is exactly what fools people who only check their balance in the early years.
Sequence risk is the silent killer
This model uses a smooth average return, which makes it a clean teaching tool but understates a real danger: sequence-of-returns risk. Real markets do not deliver a steady 3 percent. If a sharp downturn hits in your first few retirement years, you are selling shares to fund withdrawals while prices are depressed, and the portfolio may never recover even if the average return over the full period looks fine. Two retirees with identical average returns can end up worlds apart depending on whether the bad years came early or late. That is why the Guyton-Klinger guardrail approach, cutting spending after poor years and raising it after strong ones, can support a higher starting rate than a rigid fixed withdrawal.
Reading your result
If the tool reports your portfolio lasting your full horizon with a large ending balance, your withdrawal rate is conservative and you may be underspending. If it shows depletion before the horizon, lower the rate or the spending until the money survives, and treat that as a ceiling rather than a plan. My practical judgment after looking at hundreds of these: build in a cushion of at least five years beyond your planning horizon, because longevity is the risk people consistently underestimate.
Why does this tool not ask me to enter inflation separately?
Because it works in real terms. By asking for a return after inflation, it lets you keep the withdrawal constant in today's purchasing power without tracking a separate inflation series. If you would rather think in nominal numbers, add your inflation estimate back to both the return and the withdrawal, but the real-terms approach is cleaner and avoids double counting.
How does Social Security change the picture?
It lowers the withdrawal your portfolio has to cover. If Social Security or a pension funds part of your spending, the rate you apply to investments can be lower for the same lifestyle, which dramatically extends how long the portfolio lasts. Many retirees delay claiming Social Security to age 70 specifically to raise that guaranteed floor and reduce strain on the portfolio in the early, sequence-risk years.