Healthy unit economics: LTV:CAC ≥ 3:1. CAC payback period under 12 months for SaaS.
CAC = (Marketing + Sales costs) ÷ New customers acquired.
LTV = Average revenue per customer × gross margin × average customer lifespan.
3:1 is the benchmark. Above 5:1 is excellent. Below 1:1 means you lose money on every customer.