YouTube Thumbnail Resizer

What YouTube actually recommends now

YouTube no longer presents 1,280 by 720 as the recommended resolution. Its current guidance is to make the thumbnail as large as possible, specifically 3,840 by 2,160 for videos and 2,160 by 3,840 for Shorts, with a minimum width of 640 pixels for a video. It also states the aspect ratio should be 16:9 for a video, 9:16 for a Short, and 1:1 for a podcast playlist. So 1,280 by 720 is the familiar size and the right minimum practical target, but it is no longer the recommendation, and a page that says otherwise is behind the platform.

YouTube Help: add custom thumbnails

The file size limit depends on the device, and it is not small

YouTube sets different limits by upload device, which surprises people who assume one number. On mobile the limit is 2 MB for a video thumbnail, or 10 MB for a podcast. On desktop it is 50 MB. The mobile figure is the one that catches people out, because a designer on a computer will happily upload a 6 MB thumbnail and a phone uploader will be rejected. If you expect to upload from a phone, staying under 2 MB is the safe constraint regardless of how much larger the desktop limit is.

• Mobile upload: 2 MB for a video thumbnail, 10 MB for a podcast.
• Desktop upload: 50 MB.
• The mobile limit is the one that surprises people.
• Stay under 2 MB if you might upload from a phone.

NoteThe mobile limit is 2 MB. A file that uploads fine from a computer can be rejected from a phone.

A vertical video with a 16:9 thumbnail is replaced

YouTube states that a vertical video uploaded with a 16:9 custom thumbnail has that thumbnail replaced by an auto generated 4:5 version on the home, explore, and subscription pages, while the custom one still appears on the watch feed, watch history, and non mobile platforms. That is a significant detail: your carefully designed thumbnail simply will not appear in three of the places most viewers browse. It is a strong argument for preparing a 4:5 or 9:16 version as well, rather than assuming the horizontal one covers everything.

• A vertical video with a 16:9 thumbnail gets replaced on home, explore, and subscription.
• The custom thumbnail still appears on the watch feed, watch history, and desktop.
• A 4:5 or 9:16 version is worth preparing as well.
• Do not assume the horizontal thumbnail covers every surface.

NoteA 16:9 thumbnail is silently replaced on three main surfaces for a vertical video.

Text still has to survive a very small display

Whatever resolution you upload, the click decision happens in a grid or sidebar where the thumbnail may be about 210 pixels wide, and increasingly as a blurred preview on mobile. That constraint has not changed with the resolution guidance, and it is the reason a large upload does not by itself produce a better thumbnail. Four or five words is about the maximum that reads at that size, the text needs to fill a large share of the frame height, and a bold face is the only weight that survives. A face remains the strongest element you can put in a thumbnail, because it is recognisable at any small size in a way that fine detail is not.

• The click decision happens at around 210 pixels wide.
• A large upload does not by itself produce a better thumbnail.
• Four or five words is the readable maximum. Use a bold face.
• A face is the most reliable element, because it survives at any small size.
• Check the design at 210 pixels wide, not only at full size.

NoteResolution guidance changed. The 210 pixel readability constraint did not.