FIRE Calculator - Financial Independence, Retire Early & 4% Rule

Calculate your exact FIRE Number, target retirement age, Lean FIRE, Fat FIRE, Coast FIRE, and safe withdrawal rate (SWR) under the 4% Trinity Study rule.

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⚙️ Configuration & Inputs
Your current age
Stocks, index funds, 401(k), IRA
Target annual spending (e.g. $5,000 / month)
New money invested per year
Percentage withdrawn per year
Historical real S&P 500 return ~7%
📊 Results & Analysis
Your FIRE Number $1,500,000 Retire at Age 49 (in 17.4 years)
Lean FIRE Target (75% expenses) $1,125,000 Achievable at Age 46
Fat FIRE Target (150% expenses) $2,250,000 Achievable at Age 54
Coast FIRE Status Achieved! ($125k > $105k) No more contributions needed for traditional 65 retirement
Monthly Passive Retirement Cash $5,000 / month Sustained indefinitely without running out
Savings Rate Progress 33.3% of income Every 10% increase shaves ~3 years off
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The Mathematics of Financial Independence (FIRE)

Financial Independence, Retire Early (FIRE) is a movement centered on aggressive saving, mindful spending, and low-cost index fund investing to retire decades ahead of the traditional age of 65.

1. The 4% Rule & The FIRE Number

Originating from the landmark 1998 Trinity Study, the 4% Rule states that a retiree can withdraw 4% of their initial portfolio value in year one (and adjust upward for inflation every year thereafter) with a 95%+ probability that the portfolio will never be depleted over a 30-year horizon.

FIRE Number = Annual Living Expenses × 25  (assuming 4% SWR)

2. The Different Flavors of FIRE

  • Lean FIRE: Living frugally on minimal annual expenses ($30k - $45k/year).
  • Standard FIRE: Maintaining an average comfortable middle-class lifestyle ($50k - $80k/year).
  • Fat FIRE: Retiring with an abundant luxury budget ($100k - $200k+/year) with extensive travel.
  • Coast FIRE: Having accumulated enough investment principal at a young age that compound interest alone will reach your target by age 65 without saving another penny.

Frequently Asked Questions

The inverse of 4% (0.04) is 1 / 0.04 = 25. Therefore, multiplying your annual spending by 25 gives the exact principal needed so that a 4% withdrawal covers your entire budget.
Coast FIRE means your existing investments will grow to fund full retirement at age 65 without adding any more savings. Barista FIRE means your investments cover most living expenses, but you work a low-stress part-time job (such as at Starbucks) for health insurance and pocket money.
Early retirees retiring in their 30s or 40s face a longer timeline (40-60 years). Many early retirees use a more conservative 3.25% to 3.5% withdrawal rate (spending multiplied by 28.5 to 30) or use dynamic spending guardrails to guard against sequence of returns risk.