Longrun

About

Most retirement calculators show you one line: an average return, compounded, arriving at a number. No retirement has ever gone like that. Longrun does the opposite. It takes your plan and runs it against every month you could actually have retired since 1871, one at a time, each one dealt the returns and the inflation that really followed. That is 1,470 real thirty year retirements, and the answer is not a number, it is a proportion: how many of them your plan survived. The first screen shows all of them at once, every path the portfolio took, with the ones that ran out drawn in red. Underneath are the years that broke it, and you can open any of them and read it year by year, down to the year the money hit zero. It carries the whole market series inside it: the S&P Composite with dividends reinvested, a rolling ten year Treasury priced each month from that month's yield, and United States consumer prices, 1,829 months from 1871 to 2023. Every figure is adjusted for the inflation that actually happened, so a balance means what it would have bought. Five published withdrawal strategies are built in and named after the people who published them, from the plain 4% rule to the Guyton and Klinger guardrails, and the safe rate finder answers the other question: the largest amount you could have started with and still passed every single one of them. There is no account, no server, no advertising and no tracking, the app works with no connection at all, and it is a calculator rather than financial advice.

Features

• Your plan run against 1,470 real retirements, not an average
• Every historical path on one chart, with the failures in red
• Any failing year opened and read out year by year
• 152 years of real market returns and inflation, bundled
• Five published withdrawal strategies, including guardrails and VPW
• The safe withdrawal rate, found by testing rather than assumed
• Pensions, glide paths, costs and resampled futures
• Works entirely offline, with no account and no adverts