how to get the real height for google chrome and safari

how to get the real height for google chrome and safari

hi , i want to get the real height of the document by using $(document).height();

unfortunately i cant get the real height . the returning value is 1163 but when i took a look at the metric of the body it was 1193 , i don't know why this is happening maybe it bcz i'm using -box-sizing property . 

but this problem is happening just for webkit , i mean googlechrome and safari 

mozilla , opera and ie get the real height with no problem . but googlechrome and safari do not .