Frequency Capping

Frequency capping is a campaign rule that limits how many times one viewer (or, in DOOH, one screen) can see one ad in a given time window. A typical web display cap might be "3 impressions per user per day"; a CTV cap might be "1 impression per household per ad pod, 5 per week". Frequency caps prevent creative wear-out (declining response after repeated exposures) and stop campaigns from over-serving a small audience to exhaust the budget.

Implementation on the web depends on a user identifier — historically a third-party cookie, increasingly a hashed email or first-party ID. The DSP tracks impressions-per-ID in a frequency store and excludes the ID once it hits the cap. In a cookieless context (Safari, Firefox, post-2024 Chrome), frequency caps degrade to imperfect heuristics: device fingerprint hashes, contextual proxies, IP-based caps.

On DOOH, frequency capping is structurally different — there is no per-user identifier. The cap is per-screen per-loop: "this creative cannot appear more than once in the same 10-slot loop." Trillboards enforces per-loop and per-day frequency caps screen-side, plus a venue-level cap that constrains all screens in a single venue. Per-viewer caps don't make sense in DOOH because the viewer cohort changes every few minutes; the venue is the addressable unit.

Buyers should set DOOH frequency caps based on venue dwell-time profiles — short-dwell venues (QSR, convenience) need lower per-loop caps because the same viewer may not see consecutive plays.