YouTube Video Thumbnail Size

YouTube supports 4 different thumbnail sizes for videos as far as I know. You can use the one suits to your application. Also, there are two different URLs you can use to access the thumbnail images. I needed different thumbnail sizes for a demo application. The URLs to access YouTube thumbnail are:

• http://img.youtube.com/vi/<VideoID>/<Keyword>.jpg
• http://i.ytimg.com/vi/<VideoID>/<Keyword>.jpg

The video ID is the value for the "v" parameter in the YouTube video URL. For ex: http://www.youtube.com/watch?v=-cZ4mdrlWYM

Keyword is the file name of the thumbnail image and can be one of the following values:

• default (120x90 px)
• 1 (120x90 px)
• 2 (120x90 px)
• 3 (120x90 px)
• mqdefault (320x80 px)
• 0 (480x360 px)
• hqdefault (480x360)
• maxresdefault (Original size of the image)

So, we just need to pass the video id and keyword in the URL to access the relevant thumbnail. Let's see some example starting with smaller thumbs to larger ones:

Keyword = default | Size = 120x90 px

http://img.youtube.com/vi/-cZ4mdrlWYM/default.jpg

Keyword = 1 | Size = 120x90 px

http://img.youtube.com/vi/-cZ4mdrlWYM/1.jpg

Keyword = 2 | Size = 120x90 px

http://img.youtube.com/vi/-cZ4mdrlWYM/2.jpg

Keyword = 3 | Size = 120x90 px

http://img.youtube.com/vi/-cZ4mdrlWYM/3.jpg

Keyword = mqdefault | Size = 320x80 px
http://img.youtube.com/vi/-cZ4mdrlWYM/mqdefault.jpg

Keyword = 0 | Size = 480x360 px

http://img.youtube.com/vi/-cZ4mdrlWYM/0.jpg

Keyword = hqdefault | Size = 480x360 px 
http://img.youtube.com/vi/-cZ4mdrlWYM/hqdefault.jpg

Note: "hqdefault" is for high-quality and it's same as "0"

Keyword = maxresdefault  | Size = Original size of the image (maximum available resolution)

http://img.youtube.com/vi/-cZ4mdrlWYM/maxresdefault.jpg

The thumbnails 1, 2 & 3 are generated using the following formula:

X = Video length (in seconds)
Y = X divided by 4 (in seconds)
Y is the 1st thumbnail or 1.jpg
2 times Y (in seconds) is the 2nd thumbnail (poster frame) or 2.jpg
3 times Y (in seconds) is the 3rd thumbnail or 3.jpg