Lean FIRE Calculator
Calculate your Lean FIRE number โ financial independence on a deliberately minimal budget.
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Example 1 โ Lump sum, no contributions
A = 1,00,000 ร (1.10)^10 โ โน2,59,374 โ more than 2.5ร growth
๐ What is the Lean FIRE Calculator?
Lean FIRE reaches financial independence sooner than standard FIRE by deliberately targeting a leaner, more minimal expense base rather than maintaining your current lifestyle spending โ a real tradeoff between an earlier exit from full-time work and a thinner spending cushion afterward.
โ๏ธ How Lean FIRE is calculated
How the leaner expense base is calculated
This calculator reduces your current annual expenses by a percentage you choose, representing genuine, sustainable cuts (not aspirational ones) you would be comfortable maintaining long-term, then applies the standard 25x rule to that reduced figure.
Why the cuts need to be genuinely sustainable
A Lean FIRE number calculated against an unrealistically minimal budget that you cannot actually sustain for decades defeats the purpose โ the leaner figure should reflect spending you have actually tested and found workable, not a theoretical minimum.
The honest tradeoff at the core of Lean FIRE
Reaching financial independence sooner under Lean FIRE means accepting less spending flexibility afterward โ there is less room to absorb unexpected costs or lifestyle changes compared to a standard or Fat FIRE target.
Lean FIRE number
Lean expenses = current annual expenses ร (1 โ reduction %); FIRE number = lean expenses ร 25
๐งฎ Worked examples
Example โ 30% expense reduction
Current annual expenses โน6,00,000, targeting a 30% reduction, current portfolio โน5,00,000, investing โน30,000/month at 11% return.
โ Lean annual expense = โน4,20,000, Lean FIRE number = โน1,05,00,000, reached in approximately 11.8 years
Comparing against standard FIRE on the same income
Same starting numbers, but no expense reduction (standard FIRE target instead).
โ The standard FIRE number is meaningfully higher, requiring a longer timeline to reach โ the leaner target trades future spending flexibility for an earlier independence date
๐ก Original insights & how to use this calculator
Deciding whether Lean FIRE genuinely fits your situation
Lean FIRE works best for people who have already tested a leaner lifestyle and found it sustainable, not as a theoretical exercise โ be honest about which current expenses you could actually cut long-term before committing to this target.
Using Lean FIRE as an interim milestone
Some people treat their Lean FIRE number as an earlier checkpoint, reaching it first and then continuing to invest toward a fuller, more comfortable FIRE number afterward, rather than stopping work entirely at the lean target.
Revisiting the lean percentage as circumstances change
What feels sustainable shifts with life changes โ revisit your assumed reduction percentage periodically rather than treating it as fixed from when you first calculated it.
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๐ก Expert tips
Lean FIRE trades some lifestyle comfort for an earlier exit from full-time work โ be honest about which expenses you can actually sustain long-term.
Revisit your lean number periodically; what feels sustainable changes as life circumstances change.
โ Common questions
What's the difference between FIRE and Lean FIRE?
Lean FIRE applies the same 25x rule to a deliberately reduced, minimal expense base, reaching independence sooner but with less spending cushion.
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