Retirement Number Calculator (4% Rule)

Enter your expected annual expenses in retirement and your target withdrawal rate to see your "FIRE number" — how much you need invested.

Expected annual expenses in retirement Safe withdrawal rate (%) — 4% is the traditional default from the Trinity Study

How this works

Retirement number = annual expenses ÷ withdrawal rate
At a 4% rate, this is the same as expenses × 25 ("25x rule")

Basis: the "4% rule" originates from the 1998 Trinity Study (Cooley, Hubbard, Walz) and William Bengen's 1994 research on sustainable withdrawal rates, based on historical 30-year US market returns. It is a widely used planning heuristic, not a guarantee — actual safe rates depend on your portfolio, time horizon, and market conditions. This is not financial advice.