How it works
Each year, spending (rising with inflation) is paid first from Social Security or a pension once it starts, and the rest from savings, grossed up for the tax on withdrawals. Withdrawals come out at the start of the year and the rest grows at the return. The most you can spend is solved exactly in today's dollars and was checked against a search on the year-by-year model. Returns are shown as steady; a bad run early in retirement shortens how long savings last.