CAC
The all-in cost to win one new customer across marketing and sales.
CAC, customer acquisition cost, is the total cost of winning one new customer, across all marketing and sales spend. It is close to CPA but stricter: CPA counts every conversion, while CAC counts only first-time customers and often folds in more than ad spend.
CAC only makes sense next to lifetime value. A CAC that looks expensive on the first order can be a bargain if that customer reorders for years, which is why brands with strong repeat rates can afford to bid harder to acquire. It is also why Performance Max has a new-customer goal, and why non-brand prospecting, the part that actually brings new customers, is judged differently from brand.
Ground the lifetime-value side in verified repeat-purchase data, not an assumed number, or you will scale acquisition into a loss.
Put the number to work: the break-even ROAS calculator turns your margins into the ROAS you need, and a free Due Diligence Audit checks whether the figures you see are the ones you are getting. Back to the glossary.