Lean FIRE Calculator
Find the leaner portfolio you need to retire early on a minimalist budget, and see exactly when you'll get there. Results update as you type.
Lean FIRE uses the same formula as full FIRE with a smaller spending figure: annual spending ÷ withdrawal rate. This page ships with $25,000 of retirement spending rather than $40,000, so at a 4% withdrawal rate the target is $625,000, and the Coast FIRE number, the balance that would grow into it by 65 starting at 30, is $158,385. The other defaults are $120,000 invested, $1,000 a month, and a 7% return against 3% inflation and 0% fees, which the engine turns into a 4% real return. All four assumptions are editable under Advanced assumptions. The withdrawal rate traces to Bengen's 1994 paper and the Trinity Study; the method is on how our calculators work.
What is Lean FIRE?
Lean FIRE is financial independence on a deliberately modest budget, typically living on roughly $25,000-$40,000 a year. Because your expenses are lower, your FIRE number is lower too, so you can reach independence years earlier than someone targeting a traditional or "fat" lifestyle. The trade-off is a leaner cushion and less margin for lifestyle inflation or surprises.
How is your Lean FIRE number calculated?
Lean FIRE number = lean annual spending ÷ withdrawal rate
Enter your lean annual budget above. The calculator shows the portfolio you need and, using your current savings, contributions and real return, projects the age you'll reach it.
What does a $25,000 lean budget look like?
A lean number is only as credible as the budget behind it. Here's one way a single person might allocate $25,000 a year, not a prescription, just a sanity check that the total is livable:
| Category | Annual | Monthly |
|---|---|---|
| Housing (rent or running costs on a paid-off home) | $9,600 | $800 |
| Food and groceries | $5,400 | $450 |
| Transportation | $3,000 | $250 |
| Healthcare | $4,000 | $333 |
| Everything else (phone, clothes, fun, buffer) | $3,000 | $250 |
| Total | $25,000 | ~$2,083 |
Notice what makes this work: housing is under $1,000 a month, which usually means a low-cost area, a paid-off home, or a shared arrangement, and healthcare has its own line rather than being wished away. If your draft budget has no healthcare line, it isn't a budget yet. Build yours from real numbers, then run it through the calculator, if you're still saving toward it, the savings rate calculator shows how fast a high savings rate closes the gap.
Geographic arbitrage, the lean FIRE accelerator
Where you live is the biggest single line in a lean budget, so moving is the biggest single lever. The same lifestyle that costs $40,000 in an expensive metro can cost far less in a small city, a rural area, or abroad, and every $1,000 you shave off annual spending removes $25,000 from the portfolio you need at 4%. That's why geographic arbitrage, earning and saving in a high-cost area, then retiring somewhere cheaper, is the classic lean FIRE play. The move has to be one you'd genuinely enjoy, though: relocating somewhere you don't want to be to save money is a plan that unwinds itself within a few years.
What are the risks of Lean FIRE?
- No slack. A fat budget can absorb a bad year by cutting travel; a lean budget is already cut. That's why many lean retirees use a 3.5% withdrawal rate and keep a cash buffer.
- Lifestyle lock-in. The budget that suits you at 35 has to still suit you at 55, through partners, kids, aging parents and changing health. Leave room for your life to change shape.
- Health costs. One expensive condition can strain a lean plan more than any market crash. Insurance is non-negotiable, even when the premium hurts a small budget.
- The one-way door problem, softened. The honest mitigation is that lean FIRE rarely has to be permanent: a few hours of Barista-style part-time work covers a surprising share of a $25,000 budget, so lean retirees have an easier fallback than anyone else.
Frequently asked questions
How lean is Lean FIRE?
There's no official line, but most people use it for annual spending under about $40,000 for an individual (or roughly $50-60k for a couple). What matters is that the budget is sustainable for you long-term.
Is a lower withdrawal rate safer for Lean FIRE?
Often yes. With a tighter budget there's less room to cut in a downturn, so some lean retirees use 3.5% instead of 4%. Adjust it under "Advanced assumptions."
Should I combine Lean FIRE with Coast or Barista FIRE?
Many do. Hitting Coast FIRE on a lean budget is very achievable early, and a little Barista income makes a lean number even easier to sustain.
What if my spending creeps above my lean budget?
Every extra $1,000 of permanent annual spending adds $25,000 to the portfolio you need at a 4% withdrawal rate. Small creep is manageable if you catch it, but a lean plan has little slack by design, so track spending for a year or two before you retire to prove the budget is real, not aspirational.
Does Lean FIRE work in a high-cost city?
It's much harder, housing alone can consume most of a lean budget in an expensive metro. Many lean retirees pair the strategy with a move to a lower-cost area, which drops the same lifestyle to a much smaller annual figure and shrinks the portfolio target with it. The Lean FIRE guide covers how people make the location piece work.
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Sources and further reading
The figures and rules on this page rest on the sources below, so you can check them rather than take our word for it.
- Bengen, W. P., Determining Withdrawal Rates Using Historical Data, Journal of Financial Planning, 1994 (FPA reprint, March 2004, member access), the origin of the 4% rule
- Cooley, Hubbard and Walz, Retirement Savings: Choosing a Withdrawal Rate That Is Sustainable, AAII Journal, February 1998, the Trinity study
- How our calculators work, the formulas, defaults and tax year 2026 constants behind every figure on this site