What is the CSS ‘ch’ Unit?
“What I’ve found through random experimentation is that in proportional typefaces, 1ch
is usually wider than the average character width, usually by around 20-30%. But there are at least a few typefaces where the zero symbol is skinny with respect to the other letterforms; in such a case, 1ch is narrower than the average character width. ”
I learned about the ch
unit a few years ago and found it super interesting. Eric's work is really helpful for how to think about it and use it depending on the typeface with which you use it.