Lean FIRE Number
$0
Reach in —
Fat FIRE Number
$0
Reach in —
Portfolio Growth vs Targets
Lean FIRE vs Fat FIRE: Two Flavours of Freedom
FIRE isn't one-size-fits-all. Lean FIRE means retiring early on a deliberately modest budget — minimalist spending, often well under $40,000 a year — so your target portfolio is smaller and you reach it sooner. Fat FIRE means retiring with a comfortable or even luxurious lifestyle, which needs a much larger nest egg and usually more years of saving. Between them sits regular FIRE, and the right answer depends entirely on the life you want to fund.
Both use the same engine: your FIRE number is annual expenses divided by your withdrawal rate, which at 4% means 25 × annual expenses. This calculator computes both targets, then projects your current portfolio forward — compounding monthly and adding your contributions — to find the year each milestone is crossed.
Worked example: At a 4% rate, $30,000/year of lean spending needs $750,000, while $100,000/year of fat spending needs $2,500,000. Starting with $100,000 and investing $2,500/month at 7%, you might hit Lean FIRE in roughly 11–12 years but need around 24–25 years for Fat FIRE. That gap is the real trade-off: years of your life versus the lifestyle those years buy.
Frequently Asked Questions
What's the difference between Lean and Fat FIRE?+
Lean FIRE retires early on a modest budget (smaller FIRE number); Fat FIRE retires with a comfortable or luxurious lifestyle (much larger portfolio). Both use the same 25× math — they differ only in the size of the expenses.
How much do I need for each?+
Multiply target annual expenses by 25 (at a 4% rate). Lean FIRE often targets under ~$40k/year (≈$1M or less); Fat FIRE commonly targets six-figure spending and portfolios of $2.5M+.
Should I aim for Lean or Fat FIRE?+
It depends on the lifestyle you want and how long you'll keep working. Lean gets you out sooner with a thinner margin; Fat takes longer but funds a more comfortable, resilient retirement. Many aim somewhere in between.