FIRE Calculator
Two modes, both instant. The FIRE number mode turns annual spending and a withdrawal rate into the portfolio that covers that spending. The savings-rate mode adds what you invest today and a real return, and estimates the years to FI.
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Years to FI
Assumptions. Withdrawal rate 4%. Expected return 5% real, after inflation, not nominal. Spending stays in today's dollars. Contributions are added at the end of each year.
Savings rate is the share of take-home pay you invest. The rest is spending. Use 0 for invested assets if you are starting from zero. The return is real (after inflation), not nominal.
Already wondering if you can stop saving? Try the Coast FIRE calculator.
FIRE number
FIRE number = Annual spending ÷ withdrawal rate
The FIRE number is the portfolio that can pay your annual spending at the withdrawal rate you choose. At 4% it is 25 times spending. At 3.5% it is about 28.6 times spending. The rate is an assumption you set. This page does not hide a 4% inside the formula.
The 4% rule
The 4% rule is a planning shortcut from historical US market research: withdraw 4% of the starting portfolio in the first year, then adjust that dollar amount for inflation, and a balanced portfolio often lasted a 30-year retirement in past data. It is not a promise. A lower rate is the more cautious plan. Sequence of returns, fees, and a longer retirement can all break a rule that worked on a chart.
Years to FI
n = ln((FI + P / r) / (S + P / r)) / ln(1 + r)
S is what you have invested, P is the amount you add at the end of each year, r is the real return, and FI is the FIRE number. When the real return is zero, the years are simply the gap divided by what you save. Savings rate here is the share of take-home pay that you invest. Spending is the rest, so a 50% savings rate on $100,000 take-home means $50,000 invested and $50,000 spent.
Withdrawal rate
The withdrawal rate is the share of the FIRE number you plan to spend each year. It is the only assumption in FIRE number mode. Savings-rate mode uses the same rate to turn spending into the target, then a separate real return to estimate the years.
Real return, not nominal
The expected return is real: inflation is already removed. Spending stays in today's dollars, so the years you get are in today's purchasing power. A nominal stock-market average near 7% still has inflation in it. Typing that here would count inflation twice and make FI look closer than it is. 5% real is a common planning assumption, not a forecast.
Savings rate
The savings rate is invested money divided by take-home income, not by gross salary. Taxes and payroll deductions that never reached you are already out. A raise that you spend does not move the rate. Only the share you invest does.
What this does not do
This is a planning sketch, not a retirement projection. It ignores taxes on withdrawals, fees, a pension, Social Security, and a market that falls the year you stop working. Change the withdrawal rate and the real return and read the gap between those answers. That range is the useful part.
Frequently Asked Questions
A FIRE number is the portfolio that covers your annual spending at a withdrawal rate you choose. Divide spending by the rate: $40,000 at 4% is a $1,000,000 FIRE number, which is 25 times spending. Open this page with ?mode=number to use that mode directly. The savings-rate mode uses the same FIRE number as the target and then estimates how many years of saving it takes to get there.
Whatever you type. The field starts at 4%, the classic rule of thumb, and the result states that rate next to the FIRE number. 3% is a more cautious plan (about 33 times spending). 5% is more aggressive and historically less reliable for a long retirement. The calculator does not lock the rate.
Real, after inflation, not nominal. FIRE number mode does not use a return at all. Savings-rate mode asks for a real return so spending can stay in today's dollars. Do not enter a nominal average that still includes inflation. The assumptions line above the inputs repeats the rate and says real, not nominal.
Savings rate is the share of annual take-home pay that you invest. The rest is spending. On $80,000 take-home, a 50% savings rate means you invest $40,000 and spend $40,000. The FIRE number is that spending divided by your withdrawal rate. Gross salary is the wrong denominator, because money that never reached you was not available to invest.
The formula solves for the exact number of years, assuming each contribution arrives at the end of the year and the portfolio compounds at the real return. 16.6 years means you cross the FIRE number partway through the 17th year. A year-by-year count that only checks at each anniversary will land on the next whole year.
Yes. The calculator runs entirely in your browser and this page performs no lookups. Nothing about your figures leaves the tab. Entries are kept only in this browser (localStorage) so the page remembers them, and Reset wipes them.