What is the formula for gross rating point (GRP) in media planning, and what do reach and frequency represent?

• A. GRP = Impressions; Reach is the audience size; Frequency is the time span.
• B. GRP = Reach + Frequency; Reach is the percentage of the target audience exposed; Frequency is how often they are exposed.
• C. GRP = Cost x Audience; Reach is the exposed audience; Frequency is the budget per exposure.
• D. GRP = Reach x Frequency; Reach is the percentage of the target audience exposed; Frequency is how often they are exposed.

Answer: (D)

GRPs measure total exposure of a media plan to the target audience. The right formula multiplies reach by frequency: GRP equals Reach times Frequency. Reach is the percentage of the target audience that is exposed at least once to the message during the period. Frequency is the average number of times those exposed individuals see the message. Multiplying them combines how broad the audience is with how often they see it, giving a unitless gauge of overall exposure. For example, if 40% of the target is reached and they see the message an average of 4 times, GRPs = 160. This approach reflects total impressions relative to the audience size, rather than simply adding measures or tying directly to cost.