Recommended: 800 x 800 pixels
Tip: YouTube allows you to choose different borders for your profile photo. However, the size is always the same. Make sure the focus of your photo is centered for best results.
Max file size: 4MB
Minimum area for text and logos without being cut off: 1546 x 423 pixels
Minimum dimension for upload: 2048 x 1152 pixels
EXTRAS:
How to make the best YouTube channel art (plus 5 free templates).
https://blog.hootsuite.com/youtube-channel-art-templates/
Template: https://blog.snappa.com/wp-content/uploads/2017/08/youtube-channel-art-sizing-template.png
Across devices, your images will look different depending on the size of the screen. Here are some recommended sizes to accommodate each platform so you can get an idea where to place your branding.
Tablet: 1855 x 423 pixels
Mobile: 1546 x 423 pixels
Television: 2560 x 1,440 pixels
Desktop: 2560 x 423 pixels
Recommended: 1280 x 720 pixels (HD)
Tip: YouTube requires videos to be 1280 x 720 pixels in order to meet HD standards. This is highly suggested in order to have good image quality on your video, and to also attract viewers.
YouTube Display Ads: 300 x 250 pixels
YouTube Overlay Ads: 480 x 60 pixels
YouTube Companion Banner Ads: 300 x 250 pixels
YouTube Skippable Video Ads Length: 6 – 20 seconds
YouTube Non-skippable Video Ads Length: 12 seconds to 3 minutes (30 seconds is recommended)
YouTube Bumper Video Ads Length: 6 seconds