YouTube Thumbnail Downloader

Three of the five sizes hand you black bars

A YouTube thumbnail is a 16:9 picture, but YouTube does not store every copy of it on a 16:9 canvas. Three of the five sizes sit on a 4:3 canvas with the picture centred and a black bar filling the space above and below it, so the file is bigger than the image inside it. A 640 by 480 download carries 640 by 360 of actual picture and 120 rows of black.

That matters the moment you put one of these anywhere other than a slot the same shape. Drop a letterboxed copy into a blog post, a slide or a card and the bars come with it, which reads as a badly exported image rather than as YouTube's doing.

So there are only two sizes worth reaching for if you want the frame and nothing else: max resolution at 1280 by 720, and medium quality at 320 by 180 when you need something small. Each row above says which one you are looking at, and the dimensions beside it are read off the file that arrived rather than assumed from its name.

What people actually do with these

Mostly research. Pulling the thumbnails of the ten videos that outrank yours and putting them side by side tells you more about why they get clicked than any amount of advice does, because the pattern is usually obvious once they are next to each other: the same three colours, a face at the same size, four words at most. The other common reasons are writing about a video and needing its still to illustrate the piece, and rebuilding your own thumbnail after losing the file it came from.

The picture belongs to whoever made the video, so use it the way you would any other photograph you did not take. Once you have made your own, check how it reads at feed size in the post previewer, cut the subject out of its background with the background remover, and if it is the video itself you are after rather than its still, that is the media downloader.