Take a percentage of your portfolio in the first year, then the same amount every year after, adjusted for inflation. This runs that plan through every start year the historical record contains and reports how often it lasted.
The answer
97.1%
Taking $40,000 in the first year and holding that spending steady in today's money, 68 of the historical start years were sampled and 66 lasted the full 30 years. The worst was a plan begun in 1966, which ran out in year 28.
In 97.1% of 68 sampled sequences, under this model and these assumptions, the plan funded its floor spending every year for 30 years. ±2.0 points is sampling error alone.
What the money does
What this calculator assumed, because you weren't asked
United States, 1928–2024 (97 years) · Damodaran (NYU Stern), Annual Returns on Stock, T.Bonds and T.Bills: 1928–current · retrieved 2026-08-08
This is one country's record, and it belongs to the most successful equity market of the twentieth century. Anyone whose future resembles it will be fine; that is not the same as a promise.
This is a modelling tool, not financial advice. It never names an investment and takes no money from anyone who sells one.
A pension that starts at 67, a mortgage that ends in 2034, a partner who stops working two years after you, a year of university fees, tax. The full app takes all of it, keeps every figure on your own device, and tells you which change moves the answer most.