What's the FIRE number for lean fire on $25,000/year expenses?

FIRE number = annual expenses × (100 / SWR). For $25,000/year expenses at 4% SWR: $25,000 × 25.0 = $625,000.

How many years to reach this FIRE number?

Starting with $25,000 and saving $1,500/month at 7% real return, you reach $625,000 in 17 years — at age 47. Total contributed: $331,000; growth: $294,000.

What savings rate does this require?

$18,000/year saved out of an implied $43,000 income = 42% savings rate. At this rate, FIRE in ~17 years aligns with Mr. Money Mustache's famous "shockingly simple math" — savings rate is the single biggest lever, more than income or rate of return.

What if my real return is different?

Bump to 8% real and FIRE comes ~2-3 years sooner. Drop to 5% and it takes 3-5 years longer. Real (after-inflation) returns matter more than nominal. The S&P 500 long-run real return is ~7%; use this for retirement planning unless you want to inflate your target.

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FIRE scenario · Verified 2026-05-27

Lean FIRE on $25,000/year expenses

FIRE number: $625,000 ($25,000/year × 25.0). At 7% real return saving $1,500/month from $25,000, you reach it in 17 years — age 47. Savings rate: 42%.

FIRE number

$625,000

Years to FIRE

FIRE age

Savings rate

42%

Run your own variations

The calculator below is pre-filled with this scenario's numbers — drag any input to see how it shifts your FIRE timeline.

How this number was calculated

FIRE number  = Annual expenses × (100 / SWR)
             = $25,000 × 25.0
             = $625,000

Years to FIRE: solve   bal × (1 + r) + annual_contrib = FIRE
  starting bal = $25,000
  annual_contrib = $18,000
  r (real return) = 0.07
  → 17 years

Total contributed  = $331,000
From growth        = $294,000  (47% of FIRE number)

Math grounded in the Trinity Study (Cooley et al., 1998) and Karsten Jeske's SWR Series.

Related FIRE scenarios

Lean FIRE on $30,000/year — 750K target

→ FIRE $750,000 in 17 years (age 47)

Lean FIRE on $40K/year — $1M target

→ FIRE $1,000,000 in 17 years (age 49)

Run any FIRE scenario

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Educational projection. Future returns are not guaranteed. Sequence-of-returns risk matters for early retirees — see Karsten Jeske's SWR Series for nuanced analysis. Verified 2026-05-27.