To not have users complain you're withholding characters when you implement artificial input lengths? ;) (although e.g. Twitter does not accurately count visibl

To not have users complain you're withholding characters when you implement artificial input lengths? ;) (although e.g. Twitter does not accurately count visible characters, despite the character limit being a prominent feature, suggesting its not that important) "What size does this UI element have to fit this text in our specific mono-spaced font"?