Calculate the Financial Independence Retire Early target portfolio for your spending — and project how long it takes to reach it.
Multiply your annual spending by 25 (4% rule) for the standard FIRE target. $40,000 a year in spending → $1,000,000 FIRE number. Lean FIRE uses 5% (×20 = $800k); Fat FIRE uses a cautious 3% (×33 = $1.32M). The calculator below shows all three plus a years-to-FIRE projection from your current savings and contribution rate.
| Tier | Target | Years to Reach | Description |
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Takes about 1 minute.
The 25× shortcut. The FIRE number is the inverse of your withdrawal rate. At 4%, you need 25× annual spending (because 1/0.04 = 25). Drop to 3% and you need 33×. This is the canonical financial-independence equation — the same maths the Trinity Study used to derive the 4% rule.
Three tiers. Lean FIRE assumes you can live happily on a smaller budget — typically a paid-off home, minimal travel, no kids in expensive private school. Regular FIRE matches a middle-class lifestyle. Fat FIRE buys margin: $80-150k+ a year in spending, generous travel budget, ability to support family. Each adds 25-50% to the savings target.
Coast FIRE. A separate concept: the portfolio that, even with zero additional contributions, will compound to your full FIRE number by traditional retirement age (typically 65). At 7% real returns over 25 years, money doubles roughly three times — so Coast FIRE is your FIRE number divided by 8. Hitting Coast FIRE means you can stop saving and still retire on schedule.
Region. The framework is universal but the absolute number depends on local cost-of-living and healthcare. US early retirees pre-Medicare carry a $10-18k/person/year healthcare load that UK and SA retirees don't — bake this into the spending input.
A 35-year-old software engineer plans to spend $4,000 a month ($48,000 a year) in early retirement. Standard FIRE target = $48,000 × 25 = $1,200,000. Currently invested: $80,000. Monthly contribution: $2,000 across 401k, Roth IRA, and taxable brokerage. Expected real return: 7%.
Years to FIRE: with $80k starting and $2,000/month contributions, the calculator returns about 17 years — putting them at FIRE at 52. The Lean version ($960,000) lands at year 14 (age 49). The Fat version ($1,584,000) requires another 4 years to year 21 (age 56).
Coast FIRE is the interesting middle path. If they stop saving altogether at the moment the portfolio reaches $1.2M ÷ 2^((65-50)/10.3) ≈ $360,000 (roughly year 7-8), the existing portfolio will compound to the full $1.2M by age 65 without any further contributions. From that point onwards they could keep working only to cover current expenses — no further savings needed for retirement.
Adjusting one variable. If real returns disappoint at 5% instead of 7%, the timeline stretches from 17 to about 22 years. If they manage to bump savings to $2,500/month, it shortens from 17 to 14. The return assumption matters less than the savings rate over realistic 15-25 year horizons — savings rate is the lever you actually control.
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