What is a CTV impression and how is it counted?

A CTV impression is recorded when a video ad begins playing on a connected TV screen. Unlike display advertising, where an impression fires when a creative enters the viewport, CTV impressions are counted at ad start — the moment the first frame of video plays. Most India CTV publishers fire the impression beacon within the first two seconds of playback, aligned with the IAB VAST standard for the “impression” tracking event. The impression is counted regardless of whether the viewer watches to the end.

Discrepancies of 10–20% between DSP-reported impressions and publisher-reported impressions are common in India CTV and expected. The main reasons: (1) DSPs count the impression when the bid wins and the VAST tag is served; publishers count when the video actually starts playing on the device. Network latency, buffering, or app crashes between tag serve and playback create a gap. (2) SSAI publishers like JioHotstar stitch ads server-side, which removes the DSP’s ability to fire its own impression pixel — the DSP relies on the publisher’s reported count. (3) Third-party verification vendors (MOAT, IAS) may filter invalid impressions that the publisher counts as valid. Agree on a counting methodology before a campaign goes live.

A served impression means the ad was delivered to the device — the VAST tag was fetched and the video began playing. A viewable impression, in CTV context, means the ad played on a TV screen that was actively in use by a viewer. Because CTV screens are always full-screen and always in-view by definition (unlike a browser tab), the MRC and IAB consider all in-stream CTV video impressions to be viewable if they play for at least two consecutive seconds. In practice, India CTV buyers should not apply web viewability thresholds to CTV inventory — they are not comparable metrics.