TikTok video specs for API publishing
Last checked · sources listed at the foot of this page
The TikTok Content Posting API accepts three video content types on upload: video/mp4, video/quicktime and video/webm. The maximum duration is not a fixed number — it is returned per creator as max_video_post_duration_sec by the Query Creator Info endpoint, and it has to be read before each post.
Which video formats does the TikTok API accept?
Three content types are documented on the upload endpoint: video/mp4, video/quicktime and video/webm. In practice MP4 with H.264 video and AAC audio is the safe default — it is the combination TikTok transcodes most predictably.
| Content-Type | Container | Note |
|---|---|---|
| video/mp4 | .mp4 | The default. H.264 + AAC is the most predictable pairing through TikTok’s transcode. |
| video/quicktime | .mov | Accepted. Typically larger for the same quality, which matters on the transfer, not on the API. |
| video/webm | .webm | Accepted by the API. Rarely what a phone or an editor produces. |
What is the maximum TikTok video duration through the API?
There is no single answer, and this is the most commonly mis-stated fact about the TikTok API. The documented mechanism is a field, not a constant: max_video_post_duration_sec, returned by Query Creator Info for the account you are about to publish to.
Any page that gives you one number for "the TikTok API maximum video length" is describing one account, or guessing. The correct implementation asks per account, per post, and refuses the upload client-side when the file is longer.
How does the chunked upload work?
When you hand TikTok the file directly rather than a URL, the init call takes chunk_size and total_chunk_count, and the file is transferred in pieces.
TikTok’s upload reference does not publish numeric bounds for those two parameters, so treat any specific figure you read elsewhere as unverified. What the documentation does establish is the shape: you declare the chunking up front, then transfer.
Why does the aspect ratio not appear in the API docs?
Because the API does not enforce one. 9:16 at 1080 × 1920 is a distribution recommendation, not an upload constraint: a square or landscape file uploads successfully and then plays letterboxed in a full-screen vertical feed, which costs watch time rather than returning an error.
So this is the one spec on this page that no API response will ever tell you about, and the one that most affects how the video performs.
Frequently asked
- What video formats does the TikTok Content Posting API accept?
- Three content types are documented: video/mp4, video/quicktime and video/webm. MP4 with H.264 and AAC is the most predictable choice.
- What is the maximum video length I can post through the TikTok API?
- It varies by account. The Query Creator Info endpoint returns max_video_post_duration_sec for each creator, and that value is the limit for that account. There is no single published number.
- Does the TikTok API reject a video that is not 9:16?
- No. Aspect ratio is not an upload constraint. A non-vertical video uploads successfully and then plays with bars in a vertical feed, which usually reduces watch time.
- Why is my API-posted TikTok video only visible to me?
- Because content posted by an unaudited API client is restricted to private viewing mode. That restriction is lifted once the client passes TikTok’s audit, not by changing the privacy field.
Sources
- TikTok for Developers — Content Posting API, Upload Video — read on .
- TikTok for Developers — Query Creator Info — read on .
- TikTok for Developers — Content Posting API, Direct Post — read on .
These figures come from another company’s documentation, which can change without notice and which nothing here verifies automatically. That is why every source carries the date it was read. Sources on this page are re-read every quarter.