YouTube video thumbnails sizes and formats

youtube-video-thumbnails-sizes-and-formats.md

Note: YouTube is serving thumbnails from 2 servers:

• //img.youtube.com
• //i.ytimg.com

Examples are with //i.ytimg.com server just because it’s shorter, no other particular reason. You can use both.

• Player Background Thumbnail (480x360):

  WebP
  //i.ytimg.com/vi_webp/<YouTube_Video_ID_HERE>/0.webp
  
  JPG
  //i.ytimg.com/vi/<YouTube_Video_ID_HERE>/0.jpg
  

• Video frames thumbnails (120x90)

  WebP:
  Start: //i.ytimg.com/vi_webp/<YouTube_Video_ID_HERE>/1.webp
  Middle: //i.ytimg.com/vi_webp/<YouTube_Video_ID_HERE>/2.webp
  End: //i.ytimg.com/vi_webp/<YouTube_Video_ID_HERE>/3.webp
  
  JPG:
  Start: //i.ytimg.com/vi/<YouTube_Video_ID_HERE>/1.jpg
  Middle: //i.ytimg.com/vi/<YouTube_Video_ID_HERE>/2.jpg
  End: //i.ytimg.com/vi/<YouTube_Video_ID_HERE>/3.jpg
  

• Lowest quality thumbnail (120x90)

  WebP
  //i.ytimg.com/vi_webp/<YouTube_Video_ID_HERE>/default.webp
  
  JPG
  //i.ytimg.com/vi/<YouTube_Video_ID_HERE>/default.jpg
  

• Medium quality thumbnail (320x180)

  WebP
  //i.ytimg.com/vi_webp/<YouTube_Video_ID_HERE>/mqdefault.webp
  
  JPG
  //i.ytimg.com/vi/<YouTube_Video_ID_HERE>/mqdefault.jpg
  

• High quality thumbnail (480x360)

  WebP
  //i.ytimg.com/vi_webp/<YouTube_Video_ID_HERE>/hqdefault.webp
  
  JPG
  //i.ytimg.com/vi/<YouTube_Video_ID_HERE>/hqdefault.jpg
  

• Standard quality thumbnail (640x480)

  WebP
  //i.ytimg.com/vi_webp/<YouTube_Video_ID_HERE>/sddefault.webp
  
  JPG
  //i.ytimg.com/vi/<YouTube_Video_ID_HERE>/sddefault.jpg
  

• Unscaled thumbnail resolution

  WebP
  //i.ytimg.com/vi_webp/<YouTube_Video_ID_HERE>/maxresdefault.webp
  
  JPG
  //i.ytimg.com/vi/<YouTube_Video_ID_HERE>/maxresdefault.jpg
  

this is a bit old but there's also animated previews

https://i.ytimg.com/an_webp/[video id]/mqdefault_6s.webp?du=3000&sqp=[protobuf timestamp]&rs=AOn4CL[a 28-byte url-safe hash that includes the video id and other parameters]

sqp is just a unix timestamp that's 1-2 hours into the past or future, im not sure why this is the case.
both parameters are cached for 6 hours, in that timeframe hovering over a video with the same video id would result in the same hash and the same timestamp.

rs however is a bit more complex
tried it on incognito to confirm the hashing algorithm isnt fed a session specific token.
i'd assume its the video id of the hovered video, the video id of your current video, and 1-2 other things.

my best guess is that its a 168 bit sha-1 hash

unfortunately all parameters are required, so maybe it was excluded on purpose, but i just wanted to mention it here because i like fun facts