What is a gross rating point (GRP)?
A gross rating point is the standard measure of how much advertising weight a campaign delivers. One rating point is one percent of the target population. If a television spot airs in a program watched by 5 percent of a market, that spot delivers 5 rating points. Add up the rating points of every spot in a schedule and you have the campaign's GRPs.
The same number can be expressed another way: GRPs equal reach (the percentage of people who saw the ad at least once) multiplied by average frequency (how many times they saw it). A campaign that reaches 50 percent of its audience an average of four times delivers 200 GRPs. Because the count is gross, people who see the ad more than once are counted every time. That is why GRPs can run well past 100: a few hundred over a flight is common for a national television campaign.
Why it matters
Why GRP matters
GRPs give planners, buyers and brands a common currency. They make a television flight, a radio schedule and an out-of-home campaign comparable, they let a brand say how much pressure it wants in a market, and they are the basis on which much broadcast media has been negotiated and priced. Cost per point, the price of one GRP, is how buyers judge whether a schedule is good value.
They also frame the strategic choice every campaign faces between reaching more people and reaching the same people more often. Two schedules with identical GRPs can have very different shapes. A launch might favor reach, getting the message to as many people as possible; a campaign for a habit or a seasonal moment might favor frequency.
In practice
How GRP works in practice
- 01
The planner starts with a target audience (adults 25 to 54, say) and a weight goal for each market and week, based on the brand's objectives and past experience. The buyer then assembles a schedule of spots or placements from ratings data, adding up the projected rating points of each until the goal is met at the best cost per point.
- 02
After the flight, the delivered GRPs are measured against what was bought, using ratings from measurement companies, and any shortfall is made good if the media owner guaranteed delivery. Increasingly, planners also use target rating points, counted only against the specific audience, and reach and frequency curves from digital and streaming platforms, so television and online video can be planned together.
Watch out
What people get wrong about GRP
Reading a big GRP number as a big audience. Because GRPs are gross, 300 of them could mean most people saw the ad three times or a small group saw it dozens of times. Without the reach and frequency behind it, the number says how much was bought, not how many people were touched. The other mistake is forgetting that GRPs measure exposure, not effect. A schedule can hit its points perfectly and still fail, because nobody remembered the ad. Weight only works when the creative earns it.
