Audience Measurement
Frequency
The average number of times a targeted individual or household is exposed to a specific advertisement within a defined campaign flight.
What is Frequency?
Frequency is calculated as Gross Impressions divided by Reach. If a campaign delivered 1,000,000 impressions and reached 250,000 unique people, average frequency is 4.0 — each reached person heard the spot four times on average. Effective frequency theory argues that behaviour rarely changes after a single exposure; repeated exposure within a tight window is what creates recall, preference, and action.
The classic 'rule of three' is a rough heuristic: most planners target at least three exposures per reached individual during a flight. Radio, with its short spot formats and high-frequency rotations, is uniquely suited to delivering high Frequency at comparatively low CPMs.
Why it matters
Consumer psychology dictates that multiple exposures are required to generate brand recall and drive action, making frequency a critical optimization metric.
Related terms
- Reach— The absolute number of distinct, individual audience members exposed to a specific advertisement or campaign at least once.
- OES (Optimum Effective Scheduling)— A mathematical scheduling strategy explicitly designed to reach a majority of a station's audience three or more times within a single week.
- Frequency Capping— A technological limit placed on how many times a specific user IP or device ID can be served the exact same digital ad within a timeframe.
- Aided Recall— A research methodology used to test audience memory retention of advertisements by providing specific prompts or hints to the respondent.