YouTube Shorts Thumbnails: Size (2160×3840), How to Add One and What Works

Can you add a custom thumbnail to a Short?

Yes. For a long time Shorts creators could only pick a frame from the video, but YouTube now supports uploading a custom Shorts thumbnail. There are two conditions: it currently works only in YouTube Studio on a computer, and your account must be verified.

The right Shorts thumbnail size

YouTube's recommendations for Shorts thumbnails:

• Aspect ratio: 9:16 (vertical)
• Recommended resolution: 2160×3840 pixels
• Minimum: 640 pixels high
• Formats: JPG or PNG
• File size: up to 50 MB when uploading from a computer

How to add a custom Shorts thumbnail

On a computer:

• Sign in to YouTube Studio
• Click Content in the left menu, then Shorts at the top
• Open the Short you want to edit
• Under Thumbnail, click Upload file and choose your 9:16 image
• Click Save — it can take a little while to show up everywhere

The vertical-video rule to know

If you upload a vertical video with a 16:9 custom thumbnail, YouTube replaces it with an auto-generated 4:5 thumbnail on the home, explore and subscriptions pages (your 16:9 image still shows in the watch feed, in history and on non-mobile platforms). For vertical content, design in 9:16 from the start.

What makes a good Shorts cover

Shorts covers appear in shelves and grids, often small, so the same rules as normal thumbnails apply — just taller.

• One subject, centred: the edges are cropped in some layouts
• Big text in the middle third, away from the bottom where captions and buttons sit
• Two to four words, or none at all
• High contrast and a clear colour, so it stands out in a grid
• The same look across a series, so viewers recognise the next part

Make a Shorts cover from your normal thumbnail

In ThumbMagic you can generate a Short's cover natively in 9:16, or export your 16:9 thumbnail as a 9:16 cover with a smart crop that keeps the subject in frame — so your long video and its Shorts look like they belong together.