Is a 4:5 video a YouTube Short? 1080x1350 on Sume Timeline

YouTube's Shorts help page (read 2026-10-08) says a Short can be up to three minutes and have a square or vertical aspect ratio. A 4:5 frame, such as 1080x1350, is taller than it is wide, so by the wording it is vertical, but the page as read does not list 4:5 by name. Render it with Timeline 1.0 (output.width: 1080, output.height: 1350) and confirm in YouTube Studio that the upload shows as a Short.

What Timeline can render

Timeline 1.0 takes even integers from 256 to 2160 for each edge. The default is 1080x1920. The price is $0.10 for each ceil output minute at any size, so the canvas does not change the bill.

Fit and a 4:5 canvas

Clips from a 9:16 generation do not fill a 4:5 frame. With the default fit: cover, the clip is scaled to fill the frame, and the extra height is cropped. A 1080x1920 clip scaled to cover 1080x1350 keeps the full width and loses 570 pixels of height (1,920 - 1,350), which is 29.7 percent of the picture. With fit: contain, nothing is lost, but there are bars. With fit: blur, the bars are filled with a blurred copy.

• cover: no bars, 570 of 1,920 rows cut.
• contain: whole picture; a 9:16 clip scaled to 1,350 high is 759 wide (1,350 x 9 / 16 = 759.4), so about 321 pixels of side bars.
• blur: whole picture and blurred fill. Pick it for a faces-near-the-edge clip.
• stretch: distorts. Avoid it.

How much smaller is the frame

A 1080x1350 frame holds 1,458,000 pixels. A 1080x1920 frame holds 2,073,600. The 4:5 frame is 70.3 percent of the 9:16 frame in pixels, and it is also less tall on a phone held upright, so on-screen text needs more margin from the top and bottom edges than it needs on 9:16. Look at one rendered still before you commit to a whole series.

Why you might choose 4:5 at all

The reason is distribution: a 4:5 file can serve a feed placement and a Short with one render. The cost is that the Short surface shows a smaller picture than a 9:16 file would. If the Short is the main goal, pick 9:16 and make the feed version a separate render; the second render is $0.10 for each minute, so the price is low.

Treat the rule as a check and not a guess: upload, open the video in Studio, and see whether it is listed under Shorts. The page also says that videos of this shape uploaded on or after 2024-10-15 count as Shorts when they are three minutes or less.