Use jQuery's innerHeight function to get the calculated height of an element, sans border and margin.

 var height = $('#myElement').innerHeight();

**Edit:**
Use jQuery's outerHeight function to get the calculated height of an element, including padding, border and optionally the margin.

 //without margin
 var height = $('#myElement').outerHeight();
 
 //with margin
 var height = $('#myElement').outerHeight(true);

**Edit 2:**
You may also compare these results with native Javascript.

 var el = document.getElementById('myElement');
 var height = el.offsetHeight;