How long can an AI video for TikTok ads be?

As long as the ad spec allows, which is longer than any AI model makes in one call. TikTok's in-feed page lists up to 10 minutes for Non-Spark ads and no duration restriction for Spark Ads (pull). The limit you hit first is the generator's: Sume's seedance-2.5 accepts 4-30 seconds per clip, and most catalog models stop at 15.

TikTok's numbers are from its TikTok Auction In-Feed Ads help page (last updated June 2026) and an August 3, 2026 Symphony announcement. Sume's are from the Video generation docs. All read 2026-09-29.

What is the limit at each step?

Three different ceilings apply, and they do not depend on each other.

Should an ad use the full 10 minutes?

TikTok's specs allow it. Its creative best practices point the other way: put the hook in the first 6 seconds and the proposition in the first 3. That is guidance for how the ad opens, and says nothing on total length, so choose the length by what the ad has to show.

Ads longer than a generator's cap are joined from several clips, which is a normal way to reach past that cap. Check the first frame of each joined clip against the last frame of the one before it, since each generation is a separate call.

How do I get past a generator's cap with Sume?

The video request parameters in Sume's docs (model, prompt, duration, resolution, aspect_ratio, frame_images and so on) include no extend option, so you chain clips instead: generate each with the length you need, then join them with Timeline 1.0, which assembles ordered video[] slots over one audio spine into an MP4 of up to 1800 seconds. The step-by-step version is in How to extend an AI video past 30 seconds.

curl -X POST https://api.sume.com/v1/video-router/generate \
  -H "Authorization: Bearer $SUME_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: ad-long-01" \
  -d '{
    "model": "seedance-2.5",
    "prompt": "A hand turns a ceramic mug on a desk, slow camera move",
    "resolution": "720p",
    "duration": 30,
    "aspect_ratio": "9:16",
    "mode": "async"
  }'

Does the length change the AI label?

The TikTok pages read for this post state no length rule for AI labeling. For a non-Spark ad, TikTok says to check the toggle This ad contains AI-generated content in Ads Manager when the ad has image, video or audio that is completely AI-generated or significantly modified by AI. Spark Ads follow the TikTok Community Guidelines policy for AI-generated content disclosure instead. Check the current page before you submit.