Not sure what your monitor size is ?
Monitor Size: Unknown
Weigh it multi use advanced digital luggage scale
10 cm ruler
4 x 4 inch square
I am using a 19" monitor at 16:10 aspect ratio (1440x900); it is correct even when changing resolution while keeping the aspect ratio the same. I have no idea if aspect ratio matters, but also keep in mind to have the page at 100% zoom (I remembered I kept the browser at 90% zoom as default).
PILE OF SHITE