LTV:CAC ratio

Lifetime value over acquisition cost: the return on each dollar spent acquiring customers. At or below 1.0 the model is unsustainable; around 3.0 is healthy; well above 5.0 often means you are under-investing in growth.

LTV:CAC = LTV / CAC

Two cautions: LTV is back-weighted (most of the value arrives late, after the churn risk), and the ratio says nothing about speed. Pair it with CAC payback to see how fast the return arrives, and segment it by cohort, because the blended ratio hides which motions actually work.