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Your FIRE number, target retirement year, and savings-rate math in one screen.
💡 The classic 4% rule implies a FIRE number of 25× annual spending. Returns here are real (after inflation), so all figures are in today's dollars — no inflation adjustment needed.
FIRE — Financial Independence, Retire Early — is the strategy of building a portfolio large enough that its returns cover your living expenses forever. Once your investments can safely pay for your life, work becomes optional. The movement grew from the 4% rule and the observation that savings rate, not income, is the real lever on how long working life lasts.
The famous 4% rule (from the Trinity study) says a portfolio can sustainably withdraw 4% of its value per year. Flip that around: your FIRE number = annual spending ÷ 0.04 = 25× your annual spending. Spend $40,000 a year → $1,000,000 target. Lean FIRE ($28k/yr) needs ~$700k; a $80k lifestyle needs $2M. Use 3.5% (28.6×) for extra safety on 40+ year retirements.
Saving more attacks the target from both sides: the portfolio grows faster andthe required number shrinks. At a 10% savings rate you're ~50 years from FIRE; at 50% it's roughly 15–17 years; at 65% it can drop under a decade. That's why this calculator shows exactly how many years each +10% of savings rate buys you — the compression effect is the whole game.
Your portfolio compounds at a real (after-inflation) return — defaults to 5%, conservative for a stock-heavy mix — on both current savings and annual contributions: balance(t) = P(1+r)t + S × ((1+r)t − 1) / r. Because everything is in today's dollars, no inflation adjustment is needed. The tool solves for the exact year the balance crosses your FIRE number and translates it into a target retirement year.
Disclaimer: This calculator is for informational and educational purposes only and does not constitute financial, investment, or legal advice. Calculated results are estimates based on the inputs you provide; actual figures may vary. Always consult a qualified professional before making financial decisions.
The FIRE Calculator lets you figure out fire calculatorinstantly, without reaching for a spreadsheet or doing the math by hand. Whether you're planning a budget, checking a loan, or working through homework, the tool applies the correct formula behind the scenes and shows the result the moment you enter your numbers.
Unlike a static chart or table, this calculator adapts to your exact inputs. You can adjust any value and see the outcome update in real time, which makes it easy to compare scenarios — for example, "what if the rate were 1% lower?" or "what if I paid an extra $50 a month?"
Common uses: people reach for this tool when they need to find a how much do i need to retire early, fire number 25x annual spending, savings rate vs years to retirement, or lean fire vs regular fire number.
Browser-based tools like this one have a few real advantages over installed software or manual methods:
The FIRE Calculator is based on the following formula:
FIRE number = annual spending ÷ SWR · balance(t) = P(1+r)ᵗ + S × ((1+r)ᵗ − 1)/r
Variables: FIRE number = Target portfolio size ($) annual spending = Expected yearly expenses in retirement ($) SWR = Safe withdrawal rate (decimal, 0.04 for 4%) P = Current portfolio balance ($) S = Annual contribution ($) r = Real annual return after inflation (decimal) t = Years until the portfolio reaches the FIRE number
The safe withdrawal rate (classic 4%) inverts into a target of 25× annual spending. The portfolio reaches it after t years of compounding current savings P at real return r with annual contributions S; the tool solves for the crossing year and re-solves at savings rate +10 points to show the compression effect.
Worked example: Step 1: spending $48,000 at a 4% SWR → FIRE number = 48,000 / 0.04 = $1,200,000. Step 2: P = $200,000, S = $30,000/year, r = 5% real. At t = 16: 1.05^16 ≈ 2.1829 → balance = 200,000 × 2.1829 + 30,000 × (2.1829 − 1)/0.05 ≈ 436,575 + 709,725 = $1,146,300. Step 3: at t = 17: 1.05^17 ≈ 2.2920 → balance ≈ 458,404 + 775,211 = $1,233,615. Step 4: interpolating for $1,200,000 gives t ≈ 16.6 years. Result: financial independence arrives in roughly 16 years 7 months at this savings pace.
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