Conversion

CAC vs CPA: which cost to put in the weekly review

CPA is media (or campaign) cost divided by conversions. A conversion might be a lead, a trial, or a sale - whatever you told the ads account to count. It is a campaign number.

CAC is total sales-and-marketing cost to get a paying customer. It should include more than the ad account: tools, people, discounts if you treat them as acquisition cost. It is a company number.

If you generate many leads and few customers, CPA can look cheap while CAC is ugly. That is the leak: lead-to-customer conversion, not the auction.

Put CPA next to the campaign. Put CAC next to LTV. Do not report “CAC” when you only divided spend by form fills.