Every other retirement calculation — saving, allocation, fees — exists to answer this one. The drawdown phase is where the plan actually meets reality. Inflation eats spending power. Markets vary. And the simple "I'll have $X by 65" math leaves out the part where you're pulling money out for 30 years.
Drop in your starting portfolio, annual withdrawal, expected return, and inflation. The model runs year by year — withdrawing your spending, growing what's left at your return rate, and (by default) increasing next year's withdrawal by inflation. The line chart shows the balance trajectory. The headline result tells you whether the portfolio depletes before your planning horizon — and if so, when.
This is a single-scenario model (constant return, constant inflation). For a real stress test against historical bad starts, see the Sequence of Returns calculator.
Illustration only. Uses a constant rate of return; actual markets vary year to year — especially the first decade (sequence-of-returns risk). Doesn't factor taxes, Social Security, RMDs, or healthcare. A real plan accounts for all of these.
The 4% default isn't a guess — it's the "4% rule", derived by financial planner William Bengen in 1994 after backtesting every 30-year retirement window since 1926. It's the withdrawal rate that survived even the worst starting decades. It's a useful anchor and an honest baseline. It's also a baseline, not a plan.
A constant-return drawdown model tells you whether the average path survives. Useful as a baseline. Dangerous as a plan. Real markets deliver the same long-term average through wildly different paths, and the early years matter disproportionately when you're withdrawing.
Two retirees with identical portfolios and identical average returns can end up with very different outcomes — entirely based on the sequence of returns in their first decade.
Four things this calc doesn't model — but a real plan must:
Sequence-of-returns risk. Bad years early in retirement hurt twice (the market drops AND you're selling shares into the decline). The Sequence of Returns calculator stress-tests your plan against the actual worst historical cohorts.
Taxes. A $60K withdrawal from a traditional IRA isn't $60K in your pocket. The actual spending power depends on your tax bracket. The order you pull from accounts (taxable, traditional, Roth) can shift effective taxes by 20%+.
Social Security and other income. If SS or a pension covers part of your spending, the portfolio is doing less work than the calc assumes. Layer those in separately.
Healthcare and long-term care. The biggest unknown in retirement spending. Costs typically rise faster than general inflation, especially in later years.
If you're within 10 years of retirement (or in it), the drawdown question is worth a thoughtful 30-minute conversation.