Would my retirement plan have survived every market since 1928?

Enter a starting balance, withdrawal rate, retirement length, stock/bond mix, fees, and a spending rule. The calculator runs the plan through every complete historical window (69 of them for 30 years) and reports how many survived, which start years ran out and when, the median ending balance in today’s dollars, and the highest fixed inflation-adjusted rate that survived every window. A second chart follows one chosen start year in detail.

$1,000,000, a 4% initial withdrawal rising with inflation, 60% stocks / 40% 10-year Treasuries rebalanced yearly, 0.25% fees, 30 years. The plan survives 65 of 69 historical retirements (94%). The four that ran short began in 1965, 1966, 1968 and 1969 — the retirements that met the 1970s inflation early. The highest rate that survived every window is about 3.7%. Raising the rate to 5% drops success to 68%; retiring in 1982 at 4% ends with several times the starting balance in real terms.

Annual S&P 500 total returns (price plus dividends), 10-year Treasury total returns, and 3-month T-bill returns 1928–2025 are from Aswath Damodaran’s historical returns dataset at NYU Stern, which draws on Federal Reserve (FRED) data. Annual CPI-U inflation is from the Federal Reserve Bank of Minneapolis / Bureau of Labor Statistics. Each year the withdrawal is taken at the start, the remainder earns that year’s blended return less the fee, and next year’s withdrawal is set by the spending rule using that year’s actual inflation. Only complete windows count.

A high historical success rate means the plan withstood the Great Depression, the 1970s stagflation, and 2000–2009 as they actually unfolded. It does not make the plan safe: the 98 years contain only about three independent 30-year periods, U.S. returns in this era were unusually strong, and a future combination of low returns and high inflation could be worse than 1966. Treat the “always survived” rate as a stress-tested floor, and pair it with the Monte Carlo view in the full plan.

Index returns before tax; annual rebalancing with no cash buffer; no Social Security, pensions, or spending changes other than the rule chosen; U.S. large-cap stocks and Treasuries only.

Confirm any decision with an official Social Security statement, your plan custodian, and a qualified adviser. See the methodology and changelog for every rule the model applies.

Where does the 4% rule come from?

William Bengen’s 1994 study and the later “Trinity study” found that a 4% initial withdrawal, adjusted for inflation, survived every 30-year U.S. retirement in the historical record for balanced portfolios. This calculator reproduces that test with data through 2025 and lets you change every assumption.

Why did retirements starting in the mid-1960s fail when 1929 survived?

The 1929 retiree suffered a crash but then benefited from deflation, which lowered spending in nominal terms. The 1966 retiree faced flat markets for 16 years while inflation ran near 7% a year, so inflation-adjusted withdrawals grew far faster than the portfolio.

Is a backtest better than Monte Carlo?

They answer different questions. The backtest shows real sequences, including how inflation and returns moved together. Monte Carlo produces thousands of paths but depends on the model’s assumptions. Use both.