How to Calculate a Failure Rate for a 60-Year Retirement

Using example data we've been discussing, the top half of the table suggests a 3.25% withdrawal rate is the fail-safe amount in all cohorts. If you go up to 3.75%, the failure rate is 5.65% for cohorts since 1926 and 6.21% for all data modeled. Cells J6 through V25 use a similar approach, but also incorporate how the S&P 500 index is doing relative to recent highs.