How accurate are real world units in CSS?

Question

I'm starting experimenting with CSS real-world modules, specifically in and cm , for printing. A.

Are these blocks based on how they will be displayed on the screen or how they will be printed on the printer? How accurate are these units?

Answer 1

According to the W3C, it is recommended to use only em , px and % for the screen, the rest for printing.

Therefore, in a print application, in and cm measurements can be accurate.

There is an excellent article in such applications:
http://meyerweb.com/eric/articles/webrev/200001.html