FIRE Calculator: When Can You Retire Early? (Free Tool)
Enter your income, expenses & assets to find your exact FIRE date. Uses the 4% rule to calculate your FIRE number, savings rate impact, and retirement age. Free, instant results.
The 4% rule as a starting point
The default FIRE number is monthly expenses × 12 × 25 — the classic rule that a portfolio of 25× annual spending can sustain 4% withdrawals. The calculator treats it as an editable starting point, not a law: you can raise the target for a conservative 3–3.5% withdrawal rate or lower it for lean-FIRE plans, and the timeline updates from the same closed-form equation.
Worked example at a hypothetical return
Earning $5,000 and spending $3,000 per month (a 40% savings rate) with $50,000 already invested and a 7% assumed return: the FIRE number is $900,000, reached in 16 years 7 months. Of that target, $448,000 comes from contributions ($50,000 plus 199 months × $2,000) and $452,000 from investment growth — compounding does the heavier lifting. Figures are illustrative scenarios, not projections.
How to Use
- Current Age — Enter your age today — the calculator adds the projected years to FIRE to show your FIRE age
- Current Assets — Enter your total investable assets right now
- Monthly Income & Expenses — Enter after-tax monthly income and spending; the difference is your monthly savings and sets your savings rate
- FIRE Number — The target defaults to 25× annual expenses (the 4% rule) but you can type any goal directly
- Annual Return Rate — Enter a hypothetical average annual return (%) for invested savings
- Calculate & Review — Click Calculate to see years and months to FIRE, your FIRE age, savings rate, total invested, and investment gain
FAQ
What is the 4% rule?
If you save 25× your annual expenses, you can withdraw 4% per year for 30+ years without depleting your portfolio. Based on the Trinity Study, it's the cornerstone of FIRE planning.
How does savings rate affect FIRE timeline?
A higher savings rate dramatically shortens your timeline. At 50% savings rate, FIRE takes ~17 years; at 70%, ~8 years; at 90%, ~3 years. Reducing expenses has a bigger impact than increasing returns.
Is FIRE realistic?
Yes, but requires planning. Factor in healthcare costs before retirement age, tax implications, and adjust the 4% rule for your country's market conditions. Many practitioners use a more conservative 3–3.5% withdrawal rate.
How does the calculator find the time to FIRE?
It solves the compound-growth equation in closed form: months = ln((FN × r + S) ÷ (A × r + S)) ÷ ln(1 + r), where FN is the FIRE number, A current assets, S monthly savings, and r the monthly return. The result is rounded up to whole months.
What do total invested and investment gain mean?
Total invested = current assets + monthly savings × months to FIRE; investment gain is the rest of the FIRE number, contributed by compounding. In the worked example below, growth supplies more than half of the target.
When does the calculator say FIRE is unreachable?
When expenses meet or exceed income there are no savings to invest, so no timeline exists. It also flags the opposite case — assets already at or above the FIRE number — as achieved, with zero months remaining.