clientHeight + offsetHeight

HTML

<div id="png">
JS
</div>

CSS

#png{
  width:80%;
  height:1000px;
  border:1px solid #f0f;
  padding:10px;
  margin:10px 0;
  float:left;
}

JavaScript

var ht = document.getElementById('png');
var clientHeight = ht.clientHeight;
var offsetHeight = ht.offsetHeight;

console.log('clientHeight - ' + clientHeight);
console.log('offsetHeight - ' + offsetHeight);