The Gross Rating Point is a common and standard measure of media delivery in advertising. One Gross Rating Point, or GRP, is the equivalent of reaching 1% of the total potential audience with one advertising message. Two GRPs is the equivalent of reaching 1% of the audience twice or 2% of the audience once, and so forth. Thus the formula for calculating GRPs for any given advertising medium (TV, print, radio, out-of-home, digital, mobile and so forth) is reach, expressed as a percentage of total potential audience, times frequency, expressed as the average number of messages each member of the reached audience receives, or RxF=GRPs. The base for measuring reach in GRP calculations is typically the largest measured population with reasonable access to media. In the United States, the base, or "universe," most commonly used is "TV Households," meaning every household with at least one television.
Gross Rating Points measure the "weight" of advertising delivery strictly as a function of ad message exposure in media, meaning that no adjustment is made for the impact or influence of different media or messages. One exposure in any medium has the same value as one exposure in any other medium. This standardization means that GRPs can be added across media types to produce one aggregate measure of the impact of a given media campaign.