What is Lean FIRE?
Lean FIRE means reaching financial independence on a deliberately modest budget, commonly $40,000 a year or less for a household. The portfolio covers all of that spending with no work income, so the number is spending divided by your withdrawal rate: $40,000 a year is $1,000,000 at 4%. A smaller number can be reached sooner, but it leaves less room for surprises such as a health bill or a long bear market.
The calculator
$40,000 a year at 4.0% is $1,000,000. From $200,000 plus $20,000 a year at 5.0% real, that is 17.4 years.
How it works
Lean FIRE at this page's $40,000 default is a $1,000,000 nest egg at 4%. From $200,000 invested plus $20,000 a year at 5% real, that is a little over 17 years of saving. Fat FIRE is the same identity at a larger spend: $150,000 a year is $3,750,000, not a different formula.
Same identity as every other FIRE number: spending divided by the withdrawal rate. The years figure inverts the ordinary-annuity future value. The Fat FIRE calculator is the other end of the same scale. Coast and Barista are the milestones on the way: Coast FIRE calculator, Barista FIRE calculator. The generic identity is the FIRE calculator.
Lean FIRE number by spending
| Annual spending | At 4% | At 3.5% | At 3.25% | At 3% |
|---|---|---|---|---|
| $25,000 | $625,000 | $714,286 | $769,231 | $833,333 |
| $30,000 | $750,000 | $857,143 | $923,077 | $1,000,000 |
| $35,000 | $875,000 | $1,000,000 | $1,076,923 | $1,166,667 |
| $40,000 | $1,000,000 | $1,142,857 | $1,230,769 | $1,333,333 |
| $45,000 | $1,125,000 | $1,285,714 | $1,384,615 | $1,500,000 |
| $50,000 | $1,250,000 | $1,428,571 | $1,538,462 | $1,666,667 |
The 4% rule was built on 30-year retirements. Retiring in your 30s or 40s can mean 50 years of withdrawals, which is why many early retirees plan at 3.25% to 3.5%, a number roughly 29 to 31 times spending, and some use 3%, which is 33 times spending.
Retiring that early also means reaching 401(k) and IRA money before 59½, when withdrawals usually carry a 10% penalty. The 72(t) SEPP calculator sizes penalty-free substantially equal periodic payments, and the Roth conversion ladder calculator plans conversions you can spend five years later.
Lean vs Chubby vs Fat FIRE
The labels describe how much you spend, not a different formula. None of the cutoffs is official; these are the rough bands people usually mean when they use each name.
| Tier | Annual spending | FIRE number at 4% | At 3.5% |
|---|---|---|---|
| Lean FIRE | Up to $40,000 | Up to $1,000,000 | Up to $1,142,857 |
| Regular FIRE | $40,000 to $70,000 | $1,000,000 to $1,750,000 | $1,142,857 to $2,000,000 |
| Chubby FIRE | $70,000 to $100,000 | $1,750,000 to $2,500,000 | $2,000,000 to $2,857,143 |
| Fat FIRE | $100,000 and up | $2,500,000 and up | $2,857,143 and up |
Chubby FIRE is the middle ground: a budget with room for travel or a bigger home, without the full Fat FIRE number. There is no separate Chubby FIRE calculator because the math does not change. Enter $70,000 to $100,000 as your spending on this page: $80,000 a year needs $2,000,000 at 4%. If part of that spending will come from part-time work, the Barista FIRE calculator sizes only the gap.
Assumptions
Contributions at year end, one real return, no fees, no taxes. The default spending figure is a reference point, not a recommendation.