YouTube Shorts ads specs: 9:16, length limits, and sound

YouTube Shorts ads must be videos uploaded to YouTube, public or unlisted. Google recommends vertical 9:16 video, and its Video reach specs list 1080×1920 for Shorts. An ad can run up to 3 minutes, but only the first 60 seconds play in the Shorts feed, so Google recommends ads under 60 seconds, and 10–30 seconds for action-oriented ads. Horizontal assets serve with a blurred top and bottom. With Sume, generate 9:16 clips or render 1080×1920, Timeline 1.0's default size.

Google's rules are quoted from three Google Ads Help pages, YouTube Shorts ads: Asset specs and best practices, Video ads specs and format requirements, and About video ad formats, read on 2026-09-27. Organic Shorts uploads follow other rules, covered in YouTube Shorts video specs. Sume facts come from Video generation and Timeline 1.0.

What are the YouTube Shorts ad specs?

How long can a YouTube Shorts ad be?

Up to 3 minutes, but plan for under 60 seconds. Only the first 60 seconds play in the Shorts feed, with an overlay at 50 seconds that lets the viewer watch the rest on the YouTube watch page. Viewers can also skip a Shorts ad at once by swiping up or down.

On Sume, one generated clip is capped at 15 seconds on most models, and seedance-2.5 and wan-3.0 go to 30 seconds. A longer ad is a Timeline 1.0 render: audio.duration_seconds (1–1800) sets the output length, so keep it under 60, or at 10–30 for an action-oriented ad.

What happens to a horizontal ad in Shorts?

Google serves it with blurred top and bottoms in the vertical Shorts experience, and its Video Enhancement feature can generate vertical assets from a horizontal one. To choose the vertical frame yourself, render a 9:16 version: in Timeline 1.0, the default cover fit crops a clip to fill the frame, and fit: "blur" pads it with a blurred copy of the frame instead of black bars (fit modes).

Does a Shorts ad need sound?

Google recommends it: use sound (music, voiceover, or both) in Shorts ads.

On Sume, generate the clips at aspect_ratio: "9:16" on POST /v1/videos (the steps for a Short-shaped video are in YouTube Shorts video specs) and join them on Timeline 1.0, whose default output is 1080×1920. Today a render's sound comes from its audio spine and an optional soundtrack bed, not from the clips, so put a Sume-hosted voiceover in audio.url and a Sume-hosted music track in soundtrack (where the voice and music come from). Timeline reads only your workspace's media.sume.com files and needs an Idempotency-Key:

curl -X POST https://api.sume.com/v1/timeline-1.0/render \
  -H "Authorization: Bearer $SUME_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: shorts-ad-001" \
  -d '{
    "audio": {
      "url": "https://media.sume.com/artifacts/artf_demo/voice.wav",
      "duration_seconds": 30
    },
    "soundtrack": { "url": "https://media.sume.com/artifacts/artf_demo/music.mp3", "duck_db": 8 },
    "video": [
      { "source_url": "https://media.sume.com/artifacts/artf_demo/hook.mp4", "start": 0, "duration": 10 },
      { "source_url": "https://media.sume.com/artifacts/artf_demo/demo.mp4", "start": 10, "duration": 12 },
      { "source_url": "https://media.sume.com/artifacts/artf_demo/offer.mp4", "start": 22, "duration": 8 }
    ]
  }'

Do AI-made Shorts ads need a label?

Google's Shorts ads page says AI regulations in the European Union, India, and New York require disclosures or labels on ads with certain AI-generated or edited assets. It suggests adding labels to the creative itself or using the AI label setting in Google Ads, and says the setting doesn't guarantee compliance with specific regulations; it points advertisers to legal guidance.