These two numbers together tell you whether your growth is actually profitable, not just whether you’re bringing in new customers. Looking at either one alone can be misleading.

Customer Acquisition Cost (CAC)

The total cost of acquiring one new customer — ad spend, sales time, marketing tools, divided by the number of new customers acquired in that period. A straightforward number, but only half the picture.

Customer Lifetime Value (CLV)

The total revenue you expect from a customer over the entire relationship, not just their first purchase. A customer who buys once for $50 has very different value than one who buys $50 monthly for two years.

Why the ratio matters more than either number alone

A common benchmark is aiming for CLV to be at least 3x your CAC — spending $50 to acquire a customer worth $150 or more over their lifetime is healthy; spending $50 to acquire a customer worth $60 total leaves very little room for anything to go wrong.

Where this gets practical

If CAC is rising, but CLV is rising faster (through better retention or higher order values), that’s healthy growth. If CAC is rising and CLV is flat, that’s a warning sign worth addressing before scaling spend further.