What Is Your FIRE Number? A Beginner's Guide
Your FIRE number is the amount of invested money you'd need to live off indefinitely without working — calculated as your annual expenses multiplied by 25. If you spend $40,000 a year, your FIRE number is $1,000,000.
Where the 25x figure comes from
This comes from the 4% rule, a widely used retirement guideline: if you withdraw 4% of your portfolio in your first year of retirement and adjust that amount for inflation each year after, a diversified portfolio has historically had a good chance of lasting 30+ years. Since 4% of a number is the same as that number divided by 25, "25 times your annual spending" and "the 4% rule" are really the same calculation, just expressed two different ways.
How to calculate your own FIRE number
- Add up what you actually spend in a year — not your income, your spending.
- Multiply that number by 25.
- That result is the portfolio size where, historically, a 4% withdrawal rate would cover your expenses.
Lean FIRE, Fat FIRE, and Coast FIRE
The basic formula shifts depending on the lifestyle you're aiming for. Lean FIRE targets a lower annual spend (a smaller number × 25). Fat FIRE targets a more comfortable annual spend (a larger number × 25). Coast FIRE is different: it's the point where your current investments alone will grow into your full FIRE number by retirement age purely through compounding, even if you stopped contributing new money today.
Try it yourself
Enter your own expenses and savings rate below to find your FIRE number and estimate the age you could reach it.
Retirement / FIRE Calculator
Find your FIRE number, see how your savings rate moves the finish line, and watch the year your portfolio can cover your life without a salary.
Your numbers
We solve for the monthly amount you need to invest.
Set a retirement age later than your current age.
Used only to show your savings rate — currently 0.0%
$0 per year — sets your FIRE number: $0
Use an inflation-adjusted figure so results are in today's money.
Your figures stay in this browser tab only — nothing is saved or sent anywhere.
Enter your numbers and click Calculate to see your results
Educational projection using a constant real return and the 4% rule. It excludes taxes, healthcare, pensions and market sequence risk. Not retirement advice.
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Portfolio growth against your FIRE number
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About this calculator
Financial independence is defined by expenses, not income. Your FIRE number is simply the portfolio large enough that a sustainable withdrawal covers your annual spending — under the 4% rule, twenty-five times that spending. Cutting annual expenses therefore does double duty: it raises how much you save each year and lowers the target you are saving toward.
That is why savings rate dominates this calculation. Someone saving half their income reaches independence in a fraction of the time of someone saving a tenth, almost regardless of the return assumption. Try holding income constant and moving the expenses slider — the finish line moves far more than it does when you change the return by a point.
Sequence-of-returns risk is the main thing this model cannot show. A severe market decline in the first years of retirement damages a portfolio far more than the same decline later, because withdrawals lock in the loss. Common responses include holding a cash buffer, keeping flexible spending, or targeting a lower withdrawal rate than 4%.
Coast FIRE is the point where your existing portfolio grows to your target without further contributions — you only need to cover living costs from income. Barista FIRE pairs a smaller portfolio with part-time work. If you retire before pensions unlock, plan a bridge account, and budget for healthcare years that are fully self-funded.
FAQ
What is the 4% rule?
It is a rule of thumb from retirement research suggesting a portfolio can support annual withdrawals of about 4% of its starting value, adjusted for inflation, for roughly thirty years. Multiplying annual expenses by 25 gives the FIRE number used here.
Is 4% still considered safe?
It is debated. Longer retirements, lower expected bond yields and higher equity valuations have led some researchers to prefer 3.25-3.5%. A lower withdrawal rate means a larger target, so treat the FIRE number as a range, not a threshold.
Does this account for inflation?
Partly. Use a real (inflation-adjusted) return assumption — for example 5% instead of 8% — and the resulting timeline and target are already expressed in today's purchasing power.
What about taxes, healthcare and pensions?
None are modelled. Early retirement in particular carries healthcare costs and account-access rules that vary enormously by country, and any state or workplace pension arriving later can materially reduce the portfolio you need.