GRP is a short for Gross Rating Point. It is the sum of ratings achieved by a specific media vehicle or schedule. It represents the percentage of the target audience reached by an advertisement. If the advertisement appears more than once, the GRP figure represents the sum of each individual GRP.
In the case of a TV advertisement that is aired 5 times reaching 50% of the target audience, it would have 250 GRP = 5 x 50% -- ie, GRPs = frequency x % reach.
by Sameh Wagdy February 19, 2008