One AI video for TikTok, LinkedIn, Reels and Threads: limits table

A single vertical 9:16 MP4 of 15 to 30 seconds, H.264, with audio and captions, under 500 MB, fits the published ad and post limits of all four platforms in the table below. Make it once on Sume, probe it, and trim only where a platform needs something shorter.

Every value comes from the platform's own page, read on 2026-10-07: TikTok's video ad specifications, LinkedIn's video ads specifications, Meta's Reels ads page and the Threads account's post on video length.

The limits

Ad specs and organic post limits differ; a blank means we did not read a value on the vendor page.

The one file that fits

Work backward from the strictest value in each column.

• Ratio 9:16 at 720x1280 or larger. LinkedIn recommends 720x1280 and TikTok needs at least 540x960.
• Frame rate under 30 for LinkedIn, so export at 24 or 25. Trim's output conform accepts fps 24, 25, 30 or 60 with precision: exact.
• MP4 with H.264 and AAC audio, under 500 MB.
• Length 15 to 30 seconds for ads, longer only for organic posts on platforms that allow it.
• Captions burned in, since each platform handles caption files differently, and LinkedIn takes SRT only.

Make and check it on Sume

Pick a model that lists 9:16 in supported_aspect_ratios; the video guide names Gemini Omni Flash 1.1 (3 to 10 s, native audio) and Seedance 2 (4 to 15 s) among them. For a longer piece, assemble clips with the timeline render, whose default output is 1080x1920.

Then use video trim with output: { fps: 24 } and precision: exact for $0.02 per job to conform the frame rate, and probe the result before upload. For a script that tests a file against several limits at once, see one probe, three verdicts.

Disclosure travels with the file

The limits are only half of the job. Each platform has its own AI label, set at upload, and a label may follow identical copies on Meta's apps. See one MP4 for Reels, Stories and Threads for the placement side, and AI generators for TikTok for model choice.