Conversion

LTV:CAC - the ratio that gives CAC a ceiling

CAC without LTV is a number with no ceiling. You cannot say whether $80 to acquire a customer is fine until you know what that customer is worth.

A common working rule is LTV at least 3× CAC, using a real LTV - repeat purchase, churn, margin - not a slide that multiplies hope by 12 months.

If you only have a first-order value, say so. Call it contribution after CAC, not LTV. Last-click ROAS is still not CAC.

Run LTV and CAC in the same review as ROAS. ROAS decides the campaign this week. The ratio decides whether the channel stays in the plan.