FIRE Calculator
Your FI number, the year work becomes optional, and whether you've already hit Coast FI
After inflation — 5% is typical planning
4% classic; 3.5% conservative
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Quick summary
Financial independence arrives when your portfolio hits 25× annual spending (the 4% rule inverted): spending $50,000/year needs $1.25M. Years to get there depend overwhelmingly on savings rate, not income — at a 45% savings rate the classic math says roughly 17-19 years from zero regardless of salary, because higher savings simultaneously accelerates the portfolio AND proves you need less. The calculator also computes Coast FI: the pot that grows to your FI number by 65 with no further contributions.
Reviewed by Simple Calculators TeamLast reviewed
For planning only — not financial or tax advice. Results are estimates based on your inputs and the stated assumptions. Confirm important decisions with a qualified professional.
How to use this calculator
- Enter the inputs requested by the calculator.
- Choose the units or options that match your situation and review the assumptions.
- Run or update the calculation to see the result.
- Review the result, breakdown, and formulas shown on the page.
- Check the inputs, units, dates, and limitations before saving or sharing the result.
Frequently asked questions
What is a FIRE number?
Annual spending ÷ safe withdrawal rate. At the classic 4%, it's 25× spending; at a more conservative 3.5%, about 28.6×. Spending is the input that matters — a $10,000/year spending cut removes $250,000 from the target, which is why FIRE culture obsesses over expenses rather than income.
How does savings rate determine years to FI?
At a 5% real return starting from zero: a 20% savings rate takes ~37 years, 40% takes ~22, 50% ~17, 65% ~10.5. The relationship is savings-rate-only because both sides of the equation scale with income. Your actual timeline improves further with any existing savings — enter yours to see it.
What is Coast FIRE?
Having enough invested that compound growth alone reaches your FI number by traditional retirement age — no further contributions needed. A 30-year-old with a $1.25M target at 5% real needs about $227k invested to coast to 65. Hitting Coast FI means every dollar you save after is accelerating the date, not securing the destination.
Is the 4% rule safe for a 50-year early retirement?
The Trinity study validated 4% over 30-year horizons; longer retirements argue for 3.25–3.75%, flexibility in spending, or partial income. Many FIRE plans also layer in Social Security later and use bond tents around the retirement date to blunt sequence-of-returns risk — treat 4% as the planning anchor, not a guarantee.
Key terms
- FI Number
- Spending ÷ withdrawal rate — the portfolio that makes work optional.
- Savings Rate
- Savings ÷ after-tax income — the dominant variable in years-to-FI.
- Coast FI
- Enough invested that growth alone reaches FI by traditional retirement age.
- Real Return
- Return after inflation — using it keeps every figure in today's dollars.
Methodology, sources & limitations
This page shows the formula, assumptions, and limitations used for this estimate. Rates, thresholds, and other time-sensitive inputs can change, so verify them against the relevant official source before relying on a result.
For our review approach and the primary sources we consult, see the methodology and source policy. If you spot an outdated figure or formula, please contact us with a correction.