What is the allowed size of a YouTube channel name (minimal length - maximal length)?
Google account name size limits are here: https://developers.google.com/youtube/faq#login_limits YouTube channel names are limited to 20, case insensitive, alphanumeric characters.
I believe the minimum length is 6 characters. I have a vague memory of watching a Randall Munroe presentation at Google where he complained that he couldn't obtain the xkcd gmail username because it was too short.