Character Count in Comment Boxes

How can we tell how many characters are allowed in a comment box if the parameters are not stated?
For instance, how many characters can we type into this comments box?
And how many characters can we type into comments boxes on other sites that don’t say until you click “Submit” that you have too many characters?
Further, when those sites say you have too many characters but still don’t say how many you can have or how many you are over, it requires cumbersome editing of comments and a hit-or-miss approach to learn what fits.
This is not the best approach if you’re posting comments in an organizational context.
When the site fails to provide the number of characters allowed, is there any way for commenters to determine what’s allowed? The need for this especially applies when the comments box lets you continue adding lines (scrolling down), but only when you click “Submit” or “Post” does it say whether you comment fits.