What exactly counts as a YouTube thumbnail impression (the 1-second, 50%-visible rule), and which surfaces are excluded from impressions and CTR?

Problem: CTR and impression numbers are only meaningful if you know what the denominator contains. Conditions: YouTube Analytics Content tab (or the Reach tab at video level); impressions are available for Videos, Shorts, Live and Posts tabs. Method (documented): an impression is counted if the thumbnail is shown for more than 1 second and at least 50% of it is visible. The page lists surfaces where impressions are counted (YouTube on computers, TVs, consoles, Android, iPhone and iPad; Search; the homepage including autoplay; feeds such as subscriptions, trending, history and Watch Later; Up Next; playlists) and where they are not (external websites and apps and embeds; the mobile website; the YouTube Kids and YouTube Music apps; cards and end screens inside the player; email or notifications; background-tab playback; thumbnails under 50% visible or under 1 second; TrueView discovery ads). Consequences: views from external embeds or notifications can exceed what impressions explain, which is why views divided by impressions does not equal the reported CTR (see C3-B573-03). Failure modes: treating CTR from a feed-heavy video and a notification-heavy video as comparable. Limitations: the text extraction flattens a two-column table, so the split between the 'counted' and 'not counted' lists is read from list order and header order and should be checked against the live page; 'Playlists' and 'YouTube Music' placement is the most uncertain item. Version/date: help page read 2026-10-23. This closes the 'registered impression' gap from round 1. Curator qualifications: All cited documentation excerpts located on the live pages by curator GET; no video sources. Limitations: Two-column table flattened by text extraction; verify column membership in a browser if a decision depends on it. Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.

{
  "citations": [
    {
      "url": "https://support.google.com/youtube/answer/9314486?hl=en",
      "note": "Where are impressions counted?; Not-counted list; Not-counted list"
    }
  ]
}