What is a customer worth over their lifetime, and how much can you pay to get one? Five inputs, one answer.
AOV × orders a year × years × margin. Profit, not revenue, so it compares honestly with CAC.
3:1 is the common target. Below 1:1 you lose money on every customer you buy.
Orders per year is the lever email moves. Flows that bring one extra order a year lift LTV for every customer at once.