What's the FIRE number for save 70% of income — mr. money mustache style?

FIRE number = annual expenses × (100 / SWR). For $30,000/year expenses at 4% SWR: $30,000 × 25.0 = $750,000.

How many years to reach this FIRE number?

Starting with $10,000 and saving $5,833/month at 7% real return, you reach $750,000 in 9 years — at age 34. Total contributed: $639,964; growth: $110,036.

What savings rate does this require?

$69,996/year saved out of an implied $99,996 income = 70% savings rate. At this rate, FIRE in ~9 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

Save 70% of income — Mr. Money Mustache style

FIRE number: $750,000 ($30,000/year × 25.0). At 7% real return saving $5,833/month from $10,000, you reach it in 9 years — age 34. Savings rate: 70%.

FIRE number

$750,000

Years to FIRE

FIRE age

Savings rate

70%

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)
             = $30,000 × 25.0
             = $750,000

Years to FIRE: solve   bal × (1 + r) + annual_contrib = FIRE
  starting bal = $10,000
  annual_contrib = $69,996
  r (real return) = 0.07
  → 9 years

Total contributed  = $639,964
From growth        = $110,036  (15% of FIRE number)

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

Related FIRE scenarios

Save 50% of income — when can you retire?

→ FIRE $1,000,000 in 15 years (age 43)

Save 30% — realistic mid-aggressive path

→ FIRE $1,250,000 in 21 years (age 51)

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.