I am doing a real estate feed for a portal and it is telling me the max length of a string should be 20,000 bytes (20kb), but I have never run across this before.
How can I measure
You have to figure out if the string is ascii encoded or encoded with a multi-byte format.
In the former case, you can just use
In the latter case you need to find the number of bytes per character.
the strlen documentation gives an example of how to do it : http://www.php.net/manual/en/function.strlen.php#72274