GRPs, TRPs, Reach and Frequency
The aggregate total (the sum) of the ratings is called Gross Rating Points or GRPs. The sum of the ratings of a specific demographic segment may be called Target Audience GRPs or more simply TRPs. The term GRPs is generic and may refer to household GRPs or to specific target segment GRPs.
Reach is the number or percent of different homes or persons exposed at least once to an advertising schedule over a specific period of time. Reach, then, excludes duplication.
Frequency is the number of times that the average household or person is exposed to the schedule among those persons reached in the specific period of time. Because it is an average frequency, dispersion of frequency of exposure will differ between specific schedules and daypart mixes.
GRPs, reach, and frequency are mathematically related in the following ways:
Source: Media Math, NTC Publishing