YouTube Shorts thumbnail file type and size: JPG or PNG, 9:16, 50 MB

For a Shorts thumbnail, YouTube asks for an image in a format such as JPG or PNG, with a 9:16 aspect ratio, 2160 by 3840 pixels, and up to 50 MB when uploaded from a computer. Custom thumbnails for Shorts can currently only be added in YouTube Studio on a computer. Sume video frames can export a frame as a PNG or JPEG to start from.

What YouTube lists

These are the values YouTube's help page gave when read on 2026-10-07.

Export a frame

POST /v1/video-frames takes format (jpeg by default, or png) and an optional max_edge from 16 to 2160. Without max_edge, frames keep the source size. A 1080x1920 source gives a 1080x1920 frame, which is 9:16 but smaller than YouTube's suggested 2160x3840. A smaller thumbnail is accepted by the stated minimum, but the page recommends the larger size.

No upscaling here

Note that max_edge clamps the long edge down and does not enlarge. If you want the full 2160x3840, render the video at that size or generate a still. See the 9:16 thumbnail post for that path.

PNG or JPEG

Choose PNG when the frame has text or sharp graphics, and JPEG when the file size matters. Both are well under 50 MB at these sizes in normal use, but check the file before uploading.