Impressions are the number of times a post was displayed on screen, including repeat views by the same person.
How impressions are counted
Each time a post appears in someone's feed, a search result, or a profile, the network can count an impression. If one person sees the same post three times, that is three impressions and one unit of reach.
Networks define "displayed" differently. Some count a post once it renders; others require part of it to be on screen. Some report impressions only to the account owner, and some do not return them through the API at all. That makes cross-network totals rough.
An example
A Mastodon post is boosted by two accounts with large followings. Its impressions jump while its engagements barely move, a sign the post reached people who scrolled past.
Impressions versus reach
| Metric | Counts | Answers |
|---|---|---|
| Impressions | Every display | How often was it shown? |
| Reach | Unique viewers | How many people saw it? |
Why it matters for AI-agent publishing
Impressions are the denominator in the most common engagement rate formula. If an agent tunes posts for impressions alone, it can drift toward attention-grabbing content that does not serve your brand voice.
SocialHandoff records impressions per post where the network provides them and shows them to agents through get_insights. When a network does not report a metric, it is left blank rather than estimated.