Crop a YouTube thumbnail
A YouTube thumbnail is 16:9. This page opens on 1280 x 720 pixels and lists every YouTube size in the picker.
SnapCut crops and sizes the photo only. It does not check your face, expression or background.
Your photo never leaves this device. To check, open your browser's developer tools, choose Network, and crop a photo: no request carries it.
YouTube recommends a thumbnail of 3840 x 2160 pixels. SnapCut opens on 1280 x 720 instead, which has the same 16:9 shape in a smaller file; that choice is ours, and the page links to the YouTube Help article it is based on. Choose Thumbnail 4K in the list if you want the larger size.
YouTube accepts JPG or PNG thumbnails up to 50 MB on a computer and 2 MB in the mobile app. A PNG of a photograph is often large, so JPEG is usually the safer format here. The result panel shows the exact file size so you can compare it with those limits.
The same list holds the Shorts thumbnail at 2160 x 3840 for vertical videos, the channel banner at 2560 x 1440, and a profile picture at 800 x 800. For the banner, YouTube advises keeping text and logos inside the central 1235 x 338 pixels and accepts images of at least 2048 x 1152.
Drag the photo to put the face or the subject where you want it, zoom in until it fills the frame, and read the enlargement warning before you download. Thumbnails are viewed small, so a close crop usually reads better than a wide one.