Lean, Regular, Fat, and Coast FIRE in one calculator. Set your spending, savings rate, and SWR — see exactly when you reach financial independence.
🔥 FIRE Calculator — Lean, Regular, Fat, and Coast FIRE in one tool. Closed-form math, instant results.
Enter Your Details
Your Results
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Your FI Number
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Years to FI
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Age at FI
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Implied Savings Rate
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Coast FI Number (today's age)
Year-by-Year Projection
Year
Age
Year-End Investments
% to FI
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Methodology & Sources
This calculator uses the closed-form FIRE projection: years = ln((FI·r + S) / (PV·r + S)) / ln(1 + r), where PV is current investments, S is annual savings (income − spending), r is the expected real return, and FI is your target number. The FI number itself is derived from your safe withdrawal rate: FI = (spending × tier multiplier) / SWR. Tier multipliers: Lean 0.7×, Regular 1.0×, Fat 2.0×, Coast 1.0× (with separate today-discounted target).
What is FIRE (Financial Independence Retire Early)?
FIRE is a movement built around aggressive saving (typically 50%+ of income) and low-cost index investing to reach financial independence decades before traditional retirement age. The "retire early" part is optional — many FIRE achievers continue working but on their own terms.
What is the 4% rule?
The 4% rule comes from the 1998 Trinity Study and the earlier Bengen (1994) paper. It found that a portfolio of 50–75% stocks and 25–50% bonds could safely sustain 4% annual withdrawals (inflation-adjusted) over a 30-year retirement with very low failure risk. For longer retirements common in FIRE, many planners use 3.0–3.5% as more conservative.
Lean FIRE vs Fat FIRE — what's the difference?
Lean FIRE means low spending in retirement (typically 0.5–0.7× a normal middle-class lifestyle). Fat FIRE means generous spending (2.0× or more — think $200,000+ a year). Regular FIRE sits in between. The cheaper you live, the smaller your FI number — Lean FIRE on $30,000 a year is $750,000; Fat FIRE on $120,000 a year is $3 million.
What is Coast FIRE?
Coast FIRE means you have enough invested today that, with no further contributions, compound growth alone will get you to a regular FI number by traditional retirement age (e.g. 65). Reach Coast FIRE and you can downshift — work less, change careers, take a sabbatical — knowing the math will catch you.
Is the 4% rule still safe in 2026?
It's debated. Bond yields and equity valuations both affect future safe withdrawal rates. Many FIRE practitioners use a "guardrails" approach (Guyton-Klinger) or a lower starting rate (3.25–3.5%) for retirements lasting 40+ years. This calculator lets you set the SWR yourself.