Frequency capping is a limit on the number of times an ad is shown to a single person within a given period. It matters most in campaigns with a small audience and in remarketing, where without a limit the same ad shows several times a day. The effect follows a curve: the first impressions increase the likelihood of a response, beyond a certain threshold the benefit declines, and at high frequency irritation appears that damages brand perception. The optimal value differs depending on the format, the length of the buying cycle and the size of the audience, so derive it from data – track how the click-through rate and conversions change as frequency rises. With a small audience and a large budget, always set a limit, otherwise the system will waste money by repeatedly showing ads to the same people.
See also: Creative fatigue, Audience exclusion, Budget pacing.
