Lean FIRE Calculator

Lean FIRE means living on a budget significantly below the average for your country — typically 30–50% lower. In the US that often means $25–40k / year per person. In India, ₹3–5 lakh / year for a single person living simply, or ₹5–8 lakh / year for a couple. The "lean" part is voluntary minimalism — small home, low transport cost, home cooking, modest discretionary. The corpus needed is roughly 25× this lean annual expense.

Regular FIRE assumes you maintain current middle-class spending in retirement — typically 25–30× current annual expenses. Lean FIRE assumes you deliberately step down spending — to maybe 50–70% of current — and use the smaller corpus that requires. Lean reaches the goal 5–10 years earlier but trades a strict budget for that freedom. Most people use Lean FIRE as a "minimum viable retirement" number, then build past it toward regular FIRE.

Harder, but possible. The biggest variables are housing (own outright) and children's education (often pushes lean over edge unless you commit to government schools / state colleges). Most "Lean FIRE families" share a few common moves: paid-off home in a tier-2 city, one car, public schooling, very limited discretionary travel. It works — but it requires alignment with your spouse on the lifestyle, not just the math.

Buffer. A Lean FIRE budget has very little room for surprise — a medical issue, a roof repair, a kid's wedding can punch through it. Most Lean FIRE practitioners build a separate "buffer corpus" of 1–3 years' expenses on top of the 25× number, or keep a part-time income stream to absorb shocks. Pure Lean FIRE with no margin works for some; for most, a "Lean + 20% buffer" is safer.

Coast FIRE is usually reachable first because it relies on compounding (not a withdrawal corpus). Many people hit Coast FIRE at age 32–38, then keep working casually until they reach Lean FIRE at 40–45 and have full freedom. The sequencing is: Coast first (retirement is solved), Lean second (you could stop working), Full FIRE third (you can stop comfortably). The calculator can show you all three numbers — Coast, Lean, Full — side by side.