Frequency capping

Frequency capping prevents ad fatigue. Without it, a small group of heavy users might see the same ad dozens of times while others never see it at all. A cap like "3 impressions per user per 24 hours" spreads the budget across more people and improves reach.

Caps are enforced by the DSP or ad server using some identifier: a cookie, a mobile ad ID, a login, or a Household ID on CTV. When identifiers are missing (for example after App Tracking Transparency on iPhones or in browsers such as Safari that block third-party cookies), capping gets harder and the same person may be counted as many different users.

Frequency is one of the most visible failures in streaming TV, where viewers often complain about seeing the same ad repeatedly in one show; this happens partly because different buying paths and SSAI systems do not share frequency data. Setting caps too low has costs too: some messages need repetition to be remembered.

Think of it like this

Frequency capping is like a shop assistant who has already offered you a sample twice and knows not to chase you round the store with a third one.

An example

A campaign with a cap of 5 per week reaches 2 million people with 8 million impressions (average frequency 4); without the cap, the same impressions reached only 1.2 million people.