The 4% rule turns a portfolio into a safe withdrawal. Enter a portfolio to see the annual and monthly income it supports, or switch modes to find the portfolio a target income needs. Both directions use the same rate.
You can withdraw $40,000 a year
A $1,000,000 portfolio at a 4.0% withdrawal rate supports $40,000 in the first year, then rises with inflation each year after.
Safe annual withdrawal
$40,000
4.0% of portfolio
Safe monthly withdrawal
$3,333
First-year figure
This calculator answers one question. The app models your whole retirement.
The 4% rule is a starting point, not a guarantee. CoastIQ runs tax-accurate projections with Monte Carlo simulation, Roth conversion analysis, and Social Security timing, all on-device with no data collection. Free to start on iPhone.
Get CoastIQ freeThe rule runs in two directions. From a portfolio to income:
safe annual withdrawal = portfolio × safe withdrawal rate
And from a target income back to the portfolio it requires:
portfolio needed = target income / safe withdrawal rate
The 4% rate comes from the Trinity study (Cooley, Hubbard and Walz, 1998). The researchers tested rolling 30-year periods of US market history and found that withdrawing 4% of the starting balance, then raising that dollar amount by inflation each year, left the portfolio intact in nearly every period. The monthly figure is the annual amount divided by 12, and it too rises with inflation over time rather than staying fixed.
The 4% figure assumes a 30-year retirement and US historical returns. Retiring early stretches the horizon to 40 or 50 years, and a weak sequence of returns in the first decade is the main risk. For those cases a starting rate of 3.25% to 3.5% is more cautious. The calculator lets you set any rate so you can see the effect directly.
To turn spending into a target portfolio, use the FIRE number calculator. To find what you need saved today to coast there, use the coast FIRE calculator or, with part-time income, the barista FIRE calculator. To find your retirement date, use the when can I retire calculator.