The sizes YouTube keeps
Every video has the same set of thumbnails at fixed addresses: full HD at 1280×720, standard at 640×480, high quality at 480×360, medium at 320×180 and a small one at 120×90. They're the picture the creator chose, or the frame YouTube picked if they didn't choose one.
The full HD version only exists when the video was uploaded in HD — older and low-resolution videos don't have it, and the tool tells you so. The 4:3 sizes (SD, HQ and the smallest) keep the 16:9 picture between black bars; the medium one is 16:9 without bars.
What people use them for
Creators download their own thumbnails to reuse them in a newsletter, a blog post, a link-in-bio page or a community post. Designers collect references before making their own. Teachers and journalists add a video's picture to a slide or an article next to the link.
Making a better thumbnail
Looking at the thumbnails that win in your niche is the fastest way to improve yours. Most share a few habits: one face with a clear expression, three words at most, strong contrast, and nothing important in the bottom-right corner, where YouTube puts the video's length.
Make yours at 1280×720 pixels (16:9), under 2 MB, as a JPG or PNG. Our image resizer has the YouTube thumbnail size ready if you start from a photo.
Who owns a thumbnail
A thumbnail is the creator's work, like the video. Downloading one to look at, to reference or to use for your own videos is fine; publishing someone else's as your own, or using it in an ad, needs their permission.
Private by design
Your browser loads the thumbnails straight from YouTube's image server. We don't see or store which videos you look up.