YouTube thumbnail sizes and URL to get them

These are based on a 16:9 ratio.

1280×720 https://i.ytimg.com/vi/[YOUTUBE VIDEO ID]/maxresdefault.jpg

640×480 https://i.ytimg.com/vi/[YOUTUBE VIDEO ID]/sddefault.jpg

480×360 https://i.ytimg.com/vi/[YOUTUBE VIDEO ID]/hqdefault.jpg

320×180 https://i.ytimg.com/vi/[YOUTUBE VIDEO ID]/mqdefault.jpg

120×90 https://i.ytimg.com/vi/[YOUTUBE VIDEO ID]/default.jpg