really no way to get byte size of variable?

Hi List Just want to make sure: Is there no way for me to easily determine the byte size occupied by a variable (regardless of type)? It might be trivial, or I'm missing the point (as per usual)... I would like to find the actual byte size that is transmitted when say a $_POST variable is sent, or how much memory a particular variable is taking up. Just want to make sure. Some of the post received so far suggest that "one character = one byte" etc, but I would love to work with something more precise if possible, also, is a variable contains a multi-dimensional array, would that "one character = one byte" formula still return a fair representation? Thanks.