CPC

CPC is total spend divided by total clicks. It is a derived metric, not something Meta bids on directly (bidding happens on impressions or results), but it is useful for diagnosing whether rising costs come from a more expensive auction (CPM up) or weaker creative (CTR down). Two ad sets can have identical CPM but very different CPC if one has double the click-through rate.

For agencies managing dozens of ad accounts, CPC trends by vertical are a fast health check: a crypto account with CPC creeping up while CPM is flat almost always means creative fatigue rather than market conditions, which tells the media buyer to refresh assets before spend keeps flowing to a declining ad.