How the target is estimated
The calculator subtracts dependable retirement income from annual spending, then divides the remaining gap by your selected withdrawal rate.
FIRE target = (annual spending − other annual income) ÷ withdrawal rate
The 4% rate is a starting scenario
A withdrawal rate is not a guarantee. Retirement length, asset allocation, taxes, fees, inflation and early market losses can change sustainability. Compare several withdrawal rates and seek qualified advice before acting.