Every Thumbnail Size YouTube Stores
YouTube generates a fixed set of thumbnail sizes for every upload and serves them from predictable addresses on i.ytimg.com. The largest, maxresdefault, is 1280×720 and only exists when the source video was uploaded at 720p or higher. Below it sit sddefault (640×480), hqdefault (480×360), mqdefault (320×180), and a 120×90 default.
When a video has no maximum-resolution version, YouTube does not return an error — it serves a small grey placeholder instead. This tool checks the returned dimensions and hides a size rather than showing you a blank grey rectangle.
What You Can Legitimately Do With a Thumbnail
Thumbnails are copyrighted by whoever made them, same as the video. Downloading one for competitive research, a design reference, a class, or commentary and criticism is ordinary fair use in most jurisdictions. Republishing someone else's thumbnail as your own video's artwork is not — and YouTube will act on a complaint.
Studying Thumbnails That Work
If you are collecting thumbnails from top performers in your niche, look for the pattern rather than the picture: how much of the frame the face occupies, how many words of text (almost always three or fewer), whether the text is readable at 320×180, and how much contrast separates subject from background. Most high-performing thumbnails survive being shrunk to phone size, which is where most of your impressions actually happen.
Once you have the pattern, our AI thumbnail generator can turn it into concepts for your own video, and the title generator will pair a headline to it.