FIRE Calculator - 4% Rule & Years to Financial Independence
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Reviewed for accuracy by Sahil, Senior Finance & Tax Editor
FIRE Calculator - 4% Rule & Years to Financial Independence
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Formula: FIRE Number = Annual Expenses / Safe Withdrawal Rate
Worked example — FIRE Number: $1,250,000 | ~18 years to FIRE | Savings rate: 37.5%
Formula
FIRE Number = Annual Expenses / Safe Withdrawal Rate
The 4% rule states that withdrawing 4% of your portfolio in year 1, then adjusting for inflation each year, has historically sustained portfolios for 30+ years (Trinity Study, 1998). This calculator shows your required portfolio = Annual Expenses / 0.04, projected depletion timeline at different withdrawal rates, and how changing the rate to 3% or 5% affects longevity.
Worked Examples
Example 1: Standard FIRE — $50k Expenses
Problem:$50,000 annual expenses, $100,000 saved, saving $30,000/year, 7% returns, 4% withdrawal rate.
Solution:FIRE Number: $50,000 / 0.04 = $1,250,000 Progress: $100,000 / $1,250,000 = 8% Savings rate: $30,000 / $80,000 = 37.5% Years to FIRE: ~18 years (with compound growth)
Result:FIRE Number: $1,250,000 | ~18 years to FIRE | Savings rate: 37.5%
Frequently Asked Questions
What is FIRE (Financial Independence, Retire Early)?
FIRE is a movement focused on extreme savings and investment to achieve financial independence much earlier than traditional retirement age. The core idea: save 50-70%+ of your income, invest aggressively, and retire when your investment portfolio can sustain your living expenses indefinitely. FIRE number = Annual Expenses / Safe Withdrawal Rate (typically 4%). With $50,000 annual expenses and 4% withdrawal rate, your FIRE number is $1,250,000.
What is the 4% rule?
The 4% rule (Trinity Study) states you can withdraw 4% of your portfolio in year one of retirement, then adjust for inflation annually, with a high probability (95%+) of not running out of money over 30 years. It assumes a 50/50 to 75/25 stock/bond allocation. Some FIRE advocates use 3.5% for extra safety (especially for 40-50 year retirements) or 5% for more aggressive spending. Your withdrawal rate is the inverse of your 'multiply by X' factor (4% = 25x expenses, 3% = 33x).
What are Lean FIRE, Fat FIRE, and Coast FIRE?
Lean FIRE: Retire with minimal expenses ($20-40k/year), often involving frugal living, geographic arbitrage, or van life. Fat FIRE: Retire with comfortable or luxury expenses ($100k+/year), requiring a much larger portfolio. Coast FIRE: Have enough invested that compound growth alone will reach your FIRE number by traditional retirement age — you still work but only to cover current expenses, not to save more. Barista FIRE: Semi-retired with part-time work for healthcare and spending money.
What is the FIRE number and how is it calculated?
Your FIRE number is the portfolio size needed to sustain your annual spending indefinitely using a chosen safe withdrawal rate. At the commonly used 4% withdrawal rate, the FIRE number is 25 times your annual expenses (1 ÷ 0.04 = 25). Someone planning to spend $50,000/year would target a $1.25 million portfolio. A more conservative 3.5% withdrawal rate — often preferred for very long, multi-decade early retirements — raises the multiple to about 28.6 times expenses instead.
What's the difference between Lean FIRE, Fat FIRE, and Barista FIRE?
Lean FIRE targets a minimal, tightly budgeted annual spending level (often under $40,000/year), requiring the smallest portfolio but the least spending flexibility. Fat FIRE targets a more generous lifestyle budget, requiring a much larger portfolio in exchange for more comfort and less restriction. Barista FIRE sits in between — retiring from a full-time career while continued part-time or lower-stress work covers a portion of expenses, reducing the portfolio required compared to full FIRE at any spending level.
Is the 4% rule still considered safe for an early retirement lasting 40-50+ years?
The original Trinity Study and Bengen research modeled a 30-year retirement horizon. Early retirees planning a 40-60 year retirement face more historical sequences where a straight 4% withdrawal rate depletes the portfolio, so many FIRE planners use a more conservative 3-3.5% withdrawal rate, or build in flexible spending (cutting back in down markets) to extend a portfolio's safe lifespan well beyond the original 30-year study window.
How does healthcare factor into a FIRE plan before Medicare eligibility at 65?
Healthcare is often the single largest unplanned expense gap for early retirees, since employer-sponsored coverage ends with the job and Medicare doesn't begin until 65. Options include ACA marketplace plans (premium subsidies depend heavily on your reported income, which early retirees can sometimes manage through Roth withdrawals or capital gains timing), COBRA continuation (typically expensive and time-limited), or part-time work specifically for its health benefits — a common reason FIRE practitioners choose the Barista FIRE variant.
What is sequence-of-returns risk and why does it matter more for FIRE retirees?
Sequence-of-returns risk is the danger that poor market returns in the first few years of retirement — even if long-run average returns are fine — permanently damage a portfolio because withdrawals during a downturn lock in losses on shares that are sold low. Early retirees face more total years of exposure to this risk than traditional retirees, making a cash buffer (1-2 years of expenses held outside the market) and flexible withdrawal strategies especially important in the first decade after leaving full-time work.
References
Reviewed for accuracy by Sahil, Senior Finance & Tax Editor · Editorial policy
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