Custom Shorts thumbnails: the size, how to set one, and what actually gets tapped.

For two years a Short's thumbnail was whatever frame YouTube grabbed. In July 2026 YouTube opened custom Shorts thumbnails to channels in the Partner Program, set from YouTube Studio on desktop. Here is what changed, what did not, and how to make one that works in the Shorts shelf.

The facts, as of July 2026

• Size: 1080 by 1920 pixels, vertical, 9:16. Same file rules as regular thumbnails: JPG, PNG or GIF, under 2 MB.
• Who can set one: channels in the YouTube Partner Program. Uploaded Shorts get the option in YouTube Studio on desktop; the mobile app still picks a frame for you.
• No A/B test for Shorts. Test and Compare, YouTube's built-in three-thumbnail test, is for regular videos only. For a Short you pick one and live with it, so it has to be right the first time.
• Where it shows: your channel's Shorts tab, search, and some shelves. In the swipe feed itself the video plays immediately, so the thumbnail matters most before the tap, on your channel page and in search.

How to set a custom Shorts thumbnail

1. Open YouTube Studio on a computer, not the phone app.
2. Upload the Short, or open an existing one under Content and filter by Shorts.
3. Under Thumbnail, choose Upload file and pick your 1080 by 1920 image.
4. Save. It can take a few minutes to show on the channel page.

If you do not see the upload option, the channel is not in the Partner Program yet, or the Short was uploaded from the app before the option existed. Re-checking from desktop usually clears it up.

What works in a Shorts thumbnail

A Shorts thumbnail lives in a grid of tall tiles on the channel page, each about a third of the screen wide. The rules that win a 16:9 feed apply harder here:

• One subject, big. The person or object should fill most of the tile. Waist up, not full body.
• Words at the top, three or four of them. The bottom of a Shorts tile carries the view count overlay. Put the words up top and keep them huge.
• Contrast over color. A solid ground in the opposite color of the subject beats a busy photo background. If the background must be the footage, darken it and outline the subject.
• Match the first frame's energy. The thumbnail is a promise; the first second of the Short pays it off.

Make one from a frame of the video itself

Most Shorts already contain the best thumbnail: a real frame, mid-action, with the real face. The work is picking that frame, cutting the subject out of the background, and putting three words on it so they still read small. That is exactly what Thumbnl does: drop the video, pick a frame (or let it pick), type the words, and get the thumbnail in both 9:16 for the Short and 16:9 for the long-form version, scored at feed size.