LinkedIn 9:16: 720x1280 is listed, Sume's 1080x1920 default is 2.25x

LinkedIn's video ad page (read 2026-10-09) lists 720x1280 for 9:16 video, with a minimum of 360x640 and a maximum of 1080x1920. Sume's Timeline 1.0 default output is 1080x1920, which is allowed but carries 2,073,600 pixels per frame against 921,600 at 720x1280, a ratio of 2.25. Set output.width to 720 and output.height to 1280 to match the listed size, and set output.fps to 24 or 25 because LinkedIn asks for less than 30 fps.

Rendering is billed by output minute, not pixels, so $0.10 for a clip up to one minute is the same at either size. The reasons to choose 720x1280 are file size and matching the page, not price.

The window

Three sizes from the same page, with pixel counts.

File size is the second reason

At the same encoder settings, a frame with 2.25 times the pixels tends to produce a larger file, so a 30-second ad at 1080x1920 gives you more bytes to upload and more to go wrong against LinkedIn's 500 MB cap on a long ad. The page lists length from 3 seconds to 30 minutes, with 15 to 30 seconds recommended, so most ads are far under the cap. The point is more relevant to a 10-minute or 30-minute video.

Sume exposes no bitrate field, so size follows from the frame size, the length and the content. Use the smaller frame if the video does not need the extra detail on a phone.

When 1080x1920 is the right call

Pick the maximum when the ad has small text, a detailed product, or a screen recording that will be shown on a large phone or a tablet. LinkedIn's page does not say the larger frame is rejected or penalized, and the default 1080x1920 is within its stated maximum. Do not read the recommended size as a requirement; read it as the size the page uses as its example.

Pick the listed 720x1280 when the video is mostly faces and motion, and when you want to match the page exactly. The upload is smaller, a reviewer sees the exact size from the page, and the 2.25x pixel count that you do not need is not paid for in bytes. A side-by-side still check from video frames takes a minute and settles the question for your footage.

The 4:5 and 16:9 neighbors

The same page lists 4:5 at 720x900 recommended with a 360x450 minimum and 1080x1350 maximum, 16:9 at 1920x1080 or 1200x675 with a 640x360 minimum, and 1:1 from 360x360 up to 1920x1920. If one master has to feed all four, render each shape from the same source rather than cropping a rendered file twice. Each Timeline render is billed on its own output minutes, so four renders of a 30-second ad are 4 x $0.10 = $0.40.

Render settings

The Timeline fields are output.width, output.height (even integers from 256 to 2160) and output.fps (24, 25, 30 or 60). Output fade_in_seconds and fade_out_seconds are optional. Fit defaults to cover, so a 1080x1920 source will be scaled to 720x1280 with no crop, since the ratios match. The plan endpoint is free and reports billable_minutes and estimated cost.

One caution on the frame rate. If you omit fps, the render takes the rate of the longest video source. A 30 fps phone clip then renders at 30, which is not less than 30. Set 25 or 24 explicitly.

{
  "audio": { "url": "https://media.sume.com/artifacts/artf_demo/vo.wav", "duration_seconds": 28 },
  "video": [
    { "source_url": "https://media.sume.com/artifacts/artf_demo/clip.mp4", "start": 0, "duration": 28 }
  ],
  "output": { "width": 720, "height": 1280, "fps": 25 }
}