Reach

An important metric in digital advertising, reach is the total number of ‘unique’ users – or the percentage of the advertiser’s target audience – who have seen an ad at least one time. For example, if an advertiser’s target audience amounted to 10,000 people, and 5,000 of those people saw the ad at least once, the reach would be 50%. Reach counts the people, not the impressions, so if one person sees the ad two times, the reach count is still one.

This differs from the impressions metric, which counts the number of times an ad is displayed, so if one person sees the ad two times, the impression count would be two.