Reels ad: use an existing post or upload a new video? Sume 9:16 file

Meta's Reels ads page lists three ways to bring an asset: upload a native video, use an image ad, or run an existing Reels post with "Use existing post". For an AI video made on Sume, upload the final 9:16 file as a native video if it is new, and use the existing post route only after the organic Reel is already live with the right label.

The options are from Meta's Reels ads page, read on 2026-10-07. Meta recommends 9:16 vertical for this placement.

The three routes

This table keeps to what the Meta page states, plus what Sume can supply.

Make the file

Check which models make 9:16 before you spend credits. GET /v1/videos/models returns supported_aspect_ratios, and the video guide states that Gemini Omni Flash 1.1 takes 16:9 or 9:16 with native audio, 3 to 10 seconds, and that Seedance 2 lists 9:16 among its ratios for 4 to 15 seconds.

Meta's page says Reels default to sound on, so use a model with audio or add a track. Then probe the result with video inspect and read probe.has_audio and the dimensions before you upload.

Pick the route

Use these rules of thumb; they are ours, not Meta's.

• New AI video, paid only: native video upload. You control the exact file and the AI disclosure at upload.
• Video that already earned organic attention: existing post, so the ad keeps the post's social proof. Set the AI label on the organic post first.
• Only a product still: an image ad, and let Meta's music option do the audio, or turn the still into a video first. See the image-to-9:16 post.

Where Sume stops

Sume makes and checks the file. The docs we read do not describe posting to Meta Ads Manager, so the upload or post selection is a step in Meta's tools. Store the media.sume.com URL as the media inputs guide advises. For safe-zone and sound rules see the Reels ads brief, and for pixel limits see Facebook Reels ads specs.