What Is the FIRE Calculator?
The FIRE calculator works out how much money you need to reach Financial Independence and Retire Early, then estimates how many years that target is away. Enter your age, current savings, income, expenses, and expected returns, and it instantly shows your FIRE number, your savings rate, and the age you could stop working.
FIRE stands for Financial Independence, Retire Early — building enough invested wealth that your portfolio's returns cover your living costs. The calculator is built for anyone planning that path: aggressive savers chasing an early exit, mid-career professionals checking if they are on track, and anyone curious how their savings rate changes the timeline.
The core math is the Safe Withdrawal Rate (the 4% rule from the Trinity Study): withdrawing 4% of your portfolio in year one — adjusted for inflation after that — has historically lasted 30+ years. So your FIRE Number = Annual Expenses ÷ 0.04, the same as Annual Expenses × 25.
How to Use the FIRE Calculator
Enter your age and savings
Set your Current Age and Current Savings (your total invested assets). Drag the sliders for quick changes or type an exact figure in the input box.
Add income and expenses
Enter your Annual Income (after tax) and Annual Expenses. The calculator derives your Savings Rate automatically — the single biggest driver of how fast you reach FIRE.
Tune the investment rates
Adjust Expected Annual Return (7% default), Inflation Rate, and Safe Withdrawal Rate (4% default). Preset buttons jump to common values, and projections use real returns (return minus inflation).
Add post-FIRE income (optional)
Expecting a pension, rental income, or part-time work in retirement? Enter it in Post-FIRE Income to lower the amount your portfolio must cover — and your FIRE number with it.
Review your results
Read your FIRE Number, Years to FIRE, FIRE Age, and FIRE Date, then scroll on to compare Lean, Regular, and Fat FIRE, check Coast FIRE, study the projection chart, and open the year-by-year breakdown.
Features
FIRE Number Calculation
Your target portfolio is annual expenses divided by your Safe Withdrawal Rate — 25× expenses at the classic 4% rule.
Real-Time Interactive Inputs
Every slider or typed value updates the results instantly, so you can explore scenarios as fast as you can move the slider.
Lean, Regular & Fat FIRE
Compare three lifestyles side by side — Lean at 70% of expenses, Regular at your current spend, and Fat at 150% — each with its target and years to reach it.
Coast FIRE Tracking
See the amount you need invested now so compound growth alone hits your FIRE number by age 65 — with a clear reached or remaining status.
Portfolio Projection Chart
A visual chart plots portfolio growth against total contributions and your FIRE target line, so you can see exactly when you cross it.
Year-by-Year Breakdown
Expand a detailed table of each year's age, contributions, growth, and balance — with the FIRE year highlighted for quick reference.
Inflation-Adjusted Results
Projections use real returns (return minus inflation), so every figure is shown in today's purchasing power, not inflated future dollars.
Post-FIRE Income Support
Add a pension, rental income, or part-time work to reduce the expenses your portfolio has to cover and shrink your required FIRE number.
Multi-Currency Support
Switch currencies from the picker and every value, slider range, and result adjusts to match the selected currency.
Preset Rate Buttons
One-tap presets for expected return, inflation, and withdrawal rate let you jump to common assumptions without dragging a slider.
Frequently Asked Questions
What is a FIRE number and how do I calculate it?
Your FIRE number is the total portfolio value needed to sustain your annual expenses through investment withdrawals. It is annual expenses divided by your Safe Withdrawal Rate. At the default 4% rate, that equals 25 times your annual expenses — so $40,000 a year in spending means a $1,000,000 FIRE number.
What is the 4% rule (and the 25x rule)?
The 4% rule comes from the Trinity Study, which tested historical U.S. markets over 30-year periods. Withdrawing 4% in the first year (then adjusting for inflation) sustained portfolios in most cases. Because 4% is one twenty-fifth, the 4% rule and the "25x annual expenses" rule are two ways of stating the same target. For long early retirements (40+ years), many planners prefer a more cautious 3-3.5%.
How much do I need to retire early?
It depends almost entirely on your annual expenses, not your income. Multiply the spending you want in retirement by 25 (at a 4% withdrawal rate) to get the portfolio you need. The calculator also factors in your current savings, savings rate, and real returns to estimate how many years away that number is.
What is the difference between Lean, Regular, and Fat FIRE?
Lean FIRE targets a frugal lifestyle at 70% of your current expenses, needing less savings but more discipline. Regular FIRE maintains your current spending. Fat FIRE targets a more comfortable lifestyle at 150% of your expenses, requiring a larger portfolio but allowing more spending freedom.
What is Coast FIRE?
Coast FIRE is the amount you need invested today so that compound growth alone — with no further contributions — reaches your FIRE number by traditional retirement age (65). Once you hit it, you only need to earn enough to cover current expenses; you can stop actively saving and still retire on time.
How does inflation affect my FIRE number?
Inflation erodes purchasing power over time. This calculator applies real returns (your expected return minus inflation), so the FIRE number and every projected balance are expressed in today's money. That keeps the target meaningful rather than an inflated future figure that buys less than it looks.
How does Post-FIRE Income work?
Post-FIRE income reduces the expenses your portfolio has to fund. If you expect $10,000 a year from a pension and your expenses are $40,000, the portfolio only needs to cover $30,000 — cutting your FIRE number from $1,000,000 to $750,000 at a 4% withdrawal rate.
How accurate are these projections?
The model uses constant return and inflation rates, which gives a clean baseline rather than a guarantee. Real markets swing year to year, so treat the output as a planning estimate for goal-setting. Run a few scenarios with different return rates to see the range of likely outcomes.
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