Best resolution for YouTube videos - is better 4K than 1080p ?

Hi,
What resolution is optimal for a quality YouTube videos ? Is 4K much better than 1080p resolution ?

4K resolution is generally better than 1080p, because simply it is 4 times higher. But resolution 1080p is optimal for YouTube videos. It provides quite good video quality and the file size is not so big.

YouTube visitors usually watch videos in default quality, which is often 720p. But even the 720p resolution is good enough for many users and they are not looking for an option to change it.

So you can make a high quality YouTube videos in 4K resolution, but not many users will watch them in top quality.

Videos on YouTube may be automatically played in lower quality, if visitor's internet connection is slow. YouTube changes video resolution depending on user's internet connection speed.

This can occur often when using a mobile data and the network signal is not optimal.