Average view duration
Also called AVD · average watch duration
The average length of time viewers spend watching a video, reported by YouTube Studio in minutes and seconds rather than as a percentage.
In more detail
Average view duration and average percentage viewed are reported side by side in YouTube Studio and are often mistaken for the same figure. They are not: a 90-minute video and a 12-minute video can post a similar average percentage viewed while carrying very different average view durations, so the raw duration is the number that says how much watch time an upload is actually contributing, independent of how long it runs.
Example
An 88-minute sleep documentary that holds a 24:51 average view duration at a 28.2% average percentage viewed is delivering nearly 25 minutes of watch time per view, which is a more useful fact for watch-time-based ranking than the percentage alone conveys.
Why it matters
Watch time, the metric behind monetisation eligibility and much of YouTube's recommendation weighting, is built from average view duration multiplied by views, not from the percentage. A long video with a middling percentage viewed but a high average view duration can contribute more watch time than a shorter video with a flattering percentage, which is why long-form formats lean on this number specifically.