CPC

CPC is the average amount you pay each time someone clicks your ad.

CPC is set by an auction, not a price list — ad auction dynamics, Quality Score (Google) or relevance/ad rank equivalents (Meta), competition for the audience, and your bid strategy all move it. A rising CPC in an existing campaign usually means more advertisers are bidding on the same audience, not that the platform arbitrarily raised prices.

CPC is an input metric, not an outcome metric. A campaign can have a great CPC and a terrible CPA if the traffic doesn't convert. Don't optimize for CPC in isolation — optimize for CPA or ROAS and let CPC be a diagnostic you check, not a target you chase.