Glossary A–ZLetter G
Gross rating point (GRP)
A gross rating point, or GRP, measures a campaign's weight as gross impressions expressed as a percentage of the target group.
One GRP equals impressions amounting to one percent of the target group. The calculation is net reach in percent multiplied by the average number of impressions per person reached.
An example: a campaign reaches 40 percent of the target group, each person reached three times on average. That gives 120 GRPs. The same figure would result if 20 percent were each reached six times. Media planners use GRPs to plan campaigns across different media and periods with a common measure, for example television, posters and screens.
Because GRPs combine reach and frequency, they do not reveal how the two are distributed. Two plans with the same GRPs can have very different effects. The value also depends on how the target group and impressions are defined. For a screen network, GRPs can only be stated if a recognised audience measurement is available. Operators should always give GRPs together with target group, area, period and source.