GRP cost, also known as Gross Rating Point cost, is a metric used in advertising to measure the cost of reaching a specific target audience through a particular media channel. It takes into account the total number of people reached by an advertisement and the frequency at which it is shown. This cost is calculated by multiplying the cost per rating point by the total number of rating points achieved. In simpler terms, GRP cost is the price a company pays to reach a certain number of potential customers through their advertising efforts. It is an important factor in determining the effectiveness and efficiency of an advertising campaign.