A mathematical formula that divides the number of times an advertisement is shown by the percentage of the target audience who sees it, then multiplies the result by 100. In television ad buying, gross rating points (GRPs) are often employed to assist media planners in deciding when and where to run their adverts. GRPs can also be calculated for internet ads, albeit the math is a little too involved for this brief explanation. This is something that some planners find useful when deciding on their TV and online advertising media mix.