How this calculator works
Annual spending divided by a chosen withdrawal fraction sets a financial independence target. Income less spending determines monthly saving, or you can enter a deposit directly. All money is expressed in starting purchasing power: use a real return after inflation, fees and tax, and a deposit maintained in real terms. Deposits arrive at month end. The result is the first whole month meeting the target, within a 100-year planning horizon. A starting balance already above target gives zero waiting time. The table provides yearly balances instead of a chart.
Formula
Target = 12 x monthly spending / annual withdrawal fraction. Monthly real return i = (1 + annual real return)^(1/12) - 1. Balance after n months = P(1+i)^n + C((1+i)^n - 1)/i, or P + Cn when i = 0.
Worked example
Spending $100 a month with a 4% annual withdrawal assumption requires $30,000. Saving $1,000 a month from $0 at zero real return reaches the target in 30 months, or 2.5 years. Starting with $30,000 meets that same target immediately.
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Frequently asked questions
Is 4% guaranteed to last?
No. It is an editable planning assumption, not a guarantee. Return order, longevity, tax, changing spending and future market conditions all matter.
Should I enter nominal investment returns?
Use real returns because the spending target and deposits are held in starting purchasing power. Convert a nominal return r and inflation f using (1+r)/(1+f)-1.
Does the target include government benefits?
It uses the spending amount you enter. Subtract reliably funded spending from pensions or benefits before entering an investment-funded spending need, taking care with start dates and taxes.