4 Percent Rule Calculator

About this calculator

The 4 percent rule comes from the Trinity Study and William Bengen’s earlier research into historical US market returns, which found that withdrawing 4% of a retirement portfolio’s starting value in year one, then adjusting that dollar amount for inflation every year after, held up across nearly every rolling 30-year period in the historical record without running out of money.

It gives retirees a simple starting point for sustainable spending: a $1,000,000 portfolio supports roughly $40,000 in the first year of withdrawals, or about $3,333 a month, with future withdrawals rising alongside inflation rather than staying fixed in nominal dollars. It is a planning heuristic rather than a guarantee — sequence-of-returns risk, a shorter or longer retirement horizon, and market conditions that differ from the historical dataset can all push the safe rate up or down — so many planners today use it alongside more flexible, dynamic withdrawal strategies.

This calculator takes your portfolio value and withdrawal rate and returns the sustainable annual and monthly spending it implies.