Can a 1080x1080 square video be a 3-minute YouTube Short?

Short answer

Yes. YouTube's help page on three-minute Shorts says a Short can be up to 3 minutes long if it is square or vertical, and the YouTube Blog post on the change describes it as square or taller (read 2026-10-05). In Sume, set output.width and output.height to 1080 in a Timeline 1.0 render. At 180 seconds that is 3 billable minutes and $0.30.

Square against vertical

Square fits the YouTube rule. Vertical uses more of a phone screen. The same page says a landscape 16:9 video does not become a Short, which gives you a handle if you ever want a long video that stays a normal upload. Pick square when your subject is centered, such as a product on a table or a recipe from above, and vertical when you need to fill the screen.

What Timeline 1.0 allows

Output sizes are even integers from 256 to 2160. The fit field decides how a source that does not match the frame is placed.

A plan body for a square Short

This sketch fits a 16:9 source into the square with fit blur. The slot is 180 seconds long, and the audio spine is silent, so no sound file is needed for the plan. Plan calls are unbilled. For real sound, add audio.url and keep audio.duration_seconds at 180.

import json, os, urllib.request

key = os.environ.get("SUME_API_KEY", "")
if not key:
    raise SystemExit("set SUME_API_KEY")
body = {
    "audio": {"mode": "silence", "duration_seconds": 180},
    "video": [{"source_url": "https://media.sume.com/artifacts/artf_demo/wide.mp4",
               "start": 0, "duration": 180, "fit": "blur"}],
    "output": {"width": 1080, "height": 1080},
}
req = urllib.request.Request(
    "https://api.sume.com/v1/timeline-1.0/plan",
    data=json.dumps(body).encode(),
    headers={"Authorization": "Bearer " + key,
             "Content-Type": "application/json"},
)
print(json.load(urllib.request.urlopen(req)))

Check before you upload

Probe the result with video inspect to confirm the width, the height and that the duration is under 180 seconds. A render of exactly 180 seconds is at the line, so a few tenths under is safer. If the source is a long clip, cut the 180 seconds first with video trim and send the trimmed artifact into the timeline.

Fit matters more in a square than in a vertical frame. A 16:9 source in a 1080x1080 square shows about 1080 by 608 pixels with contain, which leaves two bars of about 236 pixels, so blur or cover is usually the better choice. A 9:16 source in a square is the reverse, with bars on the sides under contain. Look at one still with video frames before you commit to 180 seconds of footage.

For a series, pick one shape and keep it. Mixing square and vertical episodes in one season is allowed by the rules as I read them, but it makes the thumbnails and layouts inconsistent. Square also costs the same as vertical to render, so the choice is about the picture, not the price.