Short answer
TikTok's own video advertising guide names 21 to 34 seconds as the top-performing length for In-Feed ads. The specs allow far longer: auction In-Feed videos can run up to 10 minutes for non-Spark ads, and Spark Ads have no duration limit.
Specs to know
- Recommended format: vertical 9:16, at least 540×960 pixels.
- Non-Spark auction In-Feed ads: up to 10 minutes.
- Spark Ads: no video duration restriction, because they use organic TikTok posts.
How to use the range
- Hook in the opening seconds. Show the product, the game or the problem straight away.
- Make each second earn its place. Cut anything that does not move the viewer towards the action.
- Treat length as a test variable. Cut a short and a mid-length version of the same concept and let results decide.
In practice for apps
For games, show real gameplay early. For subscription apps, show the outcome the user gets, then the app doing it. Judge each length on cost per install or in-app event, and on retention, not on view-through rate alone. Refresh creatives often, because even strong ads fatigue.
Our TikTok ads spec guide covers every current format and size.
Sources checked 4 October 2026
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