What is the 4% rule in FIRE?

Originating from the 1998 Trinity Study, the 4% rule states that you can withdraw 4% of your initial portfolio value in your first year of retirement, and adjust that dollar amount for inflation each subsequent year, with a 95%+ probability that your capital will last at least 30 years in a balanced stock/bond portfolio.

What is CoastFIRE vs LeanFIRE vs FatFIRE?

LeanFIRE targets frugal retirement (typically 70-80% of average expenses). FatFIRE accommodates a luxurious lifestyle (125-150%+ of average expenses). CoastFIRE means you already have enough invested that without saving another cent, compound growth will fund traditional retirement by age 60-65.

🔥 TRINITY STUDY 4% SWR & MULTI-STRATEGY ENGINE

Universal FIRE Calculator & Freedom Timeline

Project your Financial Independence milestone, exact portfolio nest egg, and years to retirement. Compare LeanFIRE, Standard FIRE, FatFIRE, CoastFIRE, and BaristaFIRE with 100% private, client-side math.

⚙️ Your Financial Baseline

Current Age

Target Age (Opt)

Annual Take-Home Income $85,000

Annual Living Expenses $45,000

Annual savings = Income minus Expenses.

Current Invested Portfolio / Net Worth $100,000

Real Return % (Net) e.g. 7% (after inflation)

Safe Withdrawal Rate

Retirement Target Lifestyle

Your Target FIRE Number STANDARD FIRE

$1,125,000

Years to Freedom 13.8 yrs

FIRE Age Age 43

Savings Rate 47.1%

LEAN FIRE (75%) $843,750 11.4 yrs

STANDARD (100%) $1,125,000 13.8 yrs

FAT FIRE (135%) $1,518,750 16.6 yrs

COAST FIRE $105,420 Fully Coated!

📈 Net Worth Compound Trajectory Milestones

Year	Age	Contributions	Investment Gains	Portfolio Total

Recent Calculations

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The Science Behind FIRE & The 4% Rule

The FIRE movement (Financial Independence, Retire Early) centers on two mathematical levers: your savings rate and your Safe Withdrawal Rate (SWR). Unlike traditional retirement planning which focuses on absolute salary, FIRE measures financial freedom in multiples of living expenses.

The Trinity Study Formula: FIRE Number = Annual Expenses ÷ SWR
At 4.0% SWR: Multiple = 25× Annual Expenses
At 3.5% SWR: Multiple = 28.57× Annual Expenses

Savings Rate Acceleration: 10% Savings Rate = ~51 Working Years
30% Savings Rate = ~28 Working Years
50% Savings Rate = ~17 Working Years

Frequently Asked Questions

What is CoastFIRE and how is it calculated?

CoastFIRE is the financial milestone where your existing investment pot will grow to cover a traditional retirement (e.g. age 65) purely through compound growth, without requiring you to save another single dollar. You only need to earn enough from active work to cover your day-to-day living expenses.

Is a 4% withdrawal rate safe for early retirees aged 35–45?

The original Trinity Study evaluated a 30-year horizon. For an early retiree who may spend 40 to 60 years in retirement, many financial researchers recommend adopting a 3.25% to 3.5% SWR, or incorporating dynamic withdrawal strategies (such as Guyton-Klinger guardrails) to completely insulate against sequence of returns risk.