TikTok Spark Ads video requirements: 10 minutes and no format rules

Spark Ads boost a post that already lives on TikTok. TikTok's Spark Ads page says a video can be sparked if it is 10 minutes or shorter, and lists no restrictions on aspect ratio, resolution, file type, duration within that cap, bitrate or file size for the original post.

So for Spark, the spec is set by the organic upload, not by the ad. Read 2026-09-29.

What does TikTok say about Spark Ads limits?

The page gives a 10-minute maximum for videos that can be sparked and a cap of 10,000 Spark Ads per account. Caption limits for Spark posts are on the in-feed page: a maximum of 4 lines.

What should the underlying video be?

Since nothing is enforced, follow the in-feed defaults: vertical 9:16. Generate with aspect_ratio: "9:16", then upload as a normal post from your own account and authorize it as a Spark Ad in TikTok's tools; Sume does not post to TikTok.

Burn captions in first: POST /v1/video-captions costs $0.20 per job for videos up to 60 seconds and returns a new MP4 with the words drawn in.

curl -X POST https://api.sume.com/v1/video-captions \
  -H "Authorization: Bearer $SUME_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: spark-caption-001" \
  -d '{
    "video_url": "https://media.sume.com/artifacts/example/clean.mp4",
    "style": "tiktok-green",
    "language": "en"
  }'

Does AI-generated video change anything?

TikTok's Spark page as read does not add rules for generated video. TikTok has its own content policies; read them before you post.

What are the limits of this answer?

Sume cannot authorize a Spark code or publish to TikTok. TikTok's page does not promise every file is accepted; it says no listed restrictions.