YouTube channel can be pretty boring if you don't set it up. Setting YouTube's cover size is a great way to do this, and YouTube offers a lot of options in this regard to make it work on all platforms.
As much as we would like to tell you right away the size of the cover on the YouTube channel… Well, it should be 2560 × 1440, but not everything is so simple. There are some caveats and subtleties that you should keep in mind.
Google has a pretty extensive page on this topic, but we decided to take it one step further!
Art characteristics of the channel
For optimal results on all devices, Google recommends uploading a single 2560 x 1224 px image that has been optimized to fit the template below.
The new channels will have a variable width on the desktop, which means the site will scale to show more content on larger browser windows. There is a minimum size at which the site will no longer adapt and scrollbars will appear in the browser window. This will happen with a minimum channel width of 1546 x 423 pixels (this is the “safe area”,given that text and logos will not be cut off) and at a maximum width of 2560 x 423 pixels.
Integration with Google+
YouTube has been integrated with Google+. This means that every additional YouTube channel you create comes with its own Google+ page. The channel badge syncs with your Google+ page, so you'll need to change and customize it on the same site. The visible area is different on these two sites.
Channel Icon
The channel icon is fully visible on YouTube, but on Google+ it appears as a circle. Keep important content inside this circle. The full image is a square image that is at least 250 x 250 px in size.
YouTube cover size recommendations
Unlike the channel icon, the cover image is not affiliated with Google+. Check out this page on Google+ for tips on setting the image for best results.
The optimal cover size on YouTube is 2560 x 1440 px. Depending on the screen size, it is clipped to fixed breakpoints so that it can fit the image.
You can add links to up to five sites in the page header. The first site will also show the site name.
So you can use it to make a kind of "call to action" - to encourage your visitors to go to your site(s).
PSD Template
There is a PSD template (Photoshop) in order to bemore convenient. This document contains guidelines on important breakpoints.
