Frequency capping

Frequency capping is a limit on how many times the same person, browser, device or household is shown an ad, a campaign or an advertiser's ads within a set period.

Caps protect the viewer from repetition and the advertiser from paying for impressions that add little. Google Ad Manager lets traffickers set them on line items and ad units, for example three impressions per user per day (Google Ad Manager Help, accessed 9 November 2026). In programmatic auctions, the IAB Tech Lab lists caps among the non-price rules a buyer or seller may apply before choosing a winner (IAB Tech Lab, Programmatic Auction Definitions).

A cap is only as good as the identifier behind it. OpenRTB 2.6 says the exchange's user ID should stay stable long enough to support frequency capping and retargeting. Its implementation notes add that buyers count spend and frequency when the billing notice fires, so delayed notices can break caps (IAB Tech Lab, OpenRTB 2.x implementation notes, section 7.2). Where cookies are blocked or IDs reset, the same person looks like several people and sees the ad more often than planned.

Example: A car brand caps a campaign at three impressions per user per day in each of two DSPs. Neither DSP sees the other's delivery, so a reader reached through both can see the ad six times. A shared ID or one buying platform is the only way to enforce a single cap.

Related terms: reach and frequency, cookie sync, burl, user matching, household graph, ad server.

Authoritative source: Google Ad Manager Help, "About line items", section "Frequency" (accessed 9 November 2026).