FIRE Number Calculator
Calculate how much you need to retire early. Enter your annual expenses and expected withdrawal rate to find your FIRE number, then see how long it will take to get there.
How your FIRE number is calculated
Your FIRE number equals your annual expenses divided by your withdrawal rate. At 4%, this is your expenses multiplied by 25. The calculator also shows how long it will take to reach that target from your current savings, at your expected investment return and monthly contribution. The timeline uses the compound interest formula, adding contributions monthly and growing the balance at the stated return until it equals the FIRE number.
What this doesn't include
The FIRE number is a portfolio target - it does not include the impact of tax on investment income or withdrawals (which varies significantly by country and account type), healthcare costs that may be higher in early retirement, or the risk that returns are lower than assumed over your accumulation period. Nor does it model what happens if you continue to earn some income after reaching FIRE - which many people do, and which can meaningfully extend how long the portfolio lasts.
Why your FIRE timeline may feel unrealistic
The timeline is mechanically correct given the inputs, but small changes in assumptions make large differences. Increasing the annual return from 5% to 7% can shorten a 20-year timeline to 16 years. Increasing your monthly contribution by 20% can shorten it by 3–4 years. The most powerful lever is your savings rate - the percentage of income you save - rather than the investment return. Use the calculator to find which input has the biggest impact for your situation.
Frequently asked questions
What is the FIRE number?
Your FIRE number is the investment portfolio size that can sustain your annual expenses indefinitely, assuming a safe withdrawal rate. At a 4% withdrawal rate, the formula is: FIRE number = annual expenses × 25. At 3.5%, it is annual expenses × 28.6. The concept comes from the FIRE movement (Financial Independence, Retire Early), which popularised the 4% rule from the 1994 Trinity Study.
Is the 4% rule safe?
The 4% rule has historically supported a 30-year retirement in US market conditions. For longer retirements (40+ years), international portfolios, or low-return environments, 3–3.5% is more conservative. The rule is a starting point, not a guarantee. Sequence-of-returns risk - poor markets in the first 5 years of retirement - is the main threat. Some FIRE adherents use a lower withdrawal rate or maintain flexible spending to manage this.
What is lean FIRE versus fat FIRE?
Lean FIRE means retiring early on a minimal budget - typically annual expenses of £20,000–30,000 or $25,000–40,000. Fat FIRE means retiring with a larger portfolio to support higher annual spending. Barista FIRE or Coast FIRE are hybrid approaches where you reach a partial milestone and supplement with part-time income. The calculator works for any version: just enter your target annual expenses.
Does the FIRE number account for inflation?
The 4% rule was designed assuming annual inflation adjustments to your withdrawal amount - so you maintain the same purchasing power each year. If you withdraw a fixed nominal amount without inflation adjustments, your real purchasing power erodes over time. Enable the inflation adjustment field to see the portfolio in today's purchasing power, which gives a more conservative and realistic picture.
Should I include a state pension or Social Security in my FIRE calculation?
Yes. If you will receive a state pension, Social Security, or other guaranteed income at some point, subtract that annual amount from your expected annual expenses. This reduces the FIRE number you need to accumulate from investments alone. A $20,000/year Social Security benefit on $50,000 annual expenses means your portfolio only needs to fund $30,000/year - reducing your FIRE number by roughly $500,000 at a 4% withdrawal rate.
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The repayment engines behind this site are tested against worked examples published by FRED, the Bank of Canada, the Bank of England and the Reserve Bank of Australia. Found an error? Contact us