Fire Calculator
A FIRE calculator (Financial Independence, Retire Early) answers the movement’s central question: how much do you need, and how long until you get there? Enter your age, annual spending, current savings, yearly savings, expected real return, and a safe withdrawal rate to get your FIRE number, years to independence, FI age, progress, and the annual savings needed to hit a target retirement age.
The return is converted to a real (after-inflation) return: (1 + return) ÷ (1 + inflation) − 1. Leave inflation at 0 to use the return as-is, exactly like the classic version of this tool.
Worked example
Age 30, spending $40,000/yr, saved $50,000, saving $30,000/yr, 5% real return, 4% withdrawal rate: FIRE number = 40,000 / 0.04 = $1,000,000. Growing $50,000 at 5% with $30,000 yearly additions reaches $1M in 19 years: FI at about age 49. Progress: 5.0%. To be FI by 45 instead: about $41,525/yr in savings. Enter these values and the calculator reproduces every figure.
The 4% rule, honestly
In 1994, William Bengen tested withdrawal rates against historical US market data and found that withdrawing 4% of the portfolio in year one, then adjusting for inflation yearly, survived every 30-year period in his data. The Trinity Study later confirmed it. That is why 4% is the default here. It is not a law of nature: it assumed roughly 50/50 stocks and bonds, a 30-year horizon, and US history. Retiring at 35 with a 60-year horizon, or holding mostly bonds, argues for 3-3.5%. The withdrawal-rate selector lets you see exactly what conservatism costs: at 3%, the example's FIRE number jumps from $1M to $1.33M.
What the math assumes
A constant real return every year (enter returns after inflation: 5% real is roughly 7-8% nominal minus inflation), contributions at each year end, no taxes, no fees, and spending that stays flat in real terms. Reality adds sequence-of-returns risk (a crash early hurts more than the average suggests), taxes on withdrawals, and lifestyle drift. Treat the FI age as a central estimate under calm markets, and treat the savings rate as the variable you actually control: it moves the date far more than return-chasing does.
Inflation, retirement income, and taxes: the three missing inputs
Inflation. The old version of this tool asked for a real (after-inflation) return directly, which quietly assumed you had already done the conversion. Now enter your expected investment return and your expected inflation separately; the tool computes the real return as (1 + return) ÷ (1 + inflation) − 1. With 8% nominal return and 3% inflation, the real return is 4.85%, not 5%. Leave inflation at 0 and the tool behaves exactly as before.
Post-retirement income. A pension, rental income, or Social Security that arrives after you retire directly shrinks the portfolio you need: FIRE number = (spending − retirement income) ÷ withdrawal rate. With $40,000 of spending and $20,000 of post-retirement income at a 4% withdrawal rate, the number falls from $1,000,000 to $500,000, verified against the tool.
Retirement taxes. If your spending comes from pre-tax accounts, gross it up: $40,000 of spending at a 20% effective tax rate needs $50,000 of pre-tax withdrawals, pushing the 4% FIRE number to $1,250,000. Enter your expected effective rate and the tool does the gross-up.
Year-by-year projection tables
Below the headline result the tool now prints two tables. The accumulation table walks from your current age to your FI age, one row per year: start balance, growth plus savings, end balance. The retirement drawdown table then spends the portfolio down for 40 years at your real return, withdrawing your (tax-adjusted) spending each year, and tells you plainly whether the money survives the window or runs out, and at what age. No black box: every year is visible.
Frequently asked questions
What is my FIRE number?
Annual spending divided by your withdrawal rate. $40,000 at 4% is $1,000,000; at 3% it is $1,333,333.
Does the 4% rule still work?
Bengen's own updates found it held through recent history, but critics note lower bond yields and longer retirements argue for caution. The honest position: 4% is the best-researched starting point, and flexibility (spending less after down years) beats precision.
What counts as "annual expenses"?
Everything you will spend in retirement: housing, food, transport, insurance, health care, travel, taxes. Underestimating this number is the most common FIRE planning error.
Should I use nominal or real returns?
Real (after inflation), because your spending target is in today's dollars. A 7% nominal return with 2% inflation is about 5% real.
What if I am already past my FIRE number?
The calculator tells you so directly, with your progress over 100%. The remaining question is withdrawal strategy and taxes, which deserve professional advice.
This calculator is for education only and is not financial advice. Investing involves market risk; retirement plans involve taxes and longevity risk. Consult a qualified fiduciary advisor.
Does the drawdown table assume my spending stays flat?
It assumes spending stays flat in real (inflation-adjusted) terms, which is the standard planning simplification: your nominal withdrawals rise with inflation, but the table works in today's dollars so every row is comparable.