Reach vs impressions
Reach counts the unique people who saw a post; impressions count every time it was shown.
If one person sees your post three times, that is one reach and three impressions. Impressions are always equal to or higher than reach, and the gap shows how often the same people saw it.
Reach vs impressions in practice
Use reach to judge how many different people you touched, and impressions to see frequency. Platforms define and label these slightly differently, so read each platform’s own definition before comparing numbers across them.
A practical use: if impressions are much higher than reach, the same people are seeing the post repeatedly, which can be good for a message you want remembered. If both are low, the post was not shown widely, and the opening line or format is the first thing to test.
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