auctiontech beat me to the diagonal measurement request, but another way to determine screen size of monitors and TVs is the model number. The first two numerical digits in the model number will tell you the screen size. In your case - X163W - the first two digits are 16 ... this is a 16" screen. I've been a TV tech for 25 years and have only come across a couple of exceptions to that rule :-) Good luck...
level thank you for that measurement information . I live in Iowa and that monitor was clear across town in my shop. it's like 50 below 0 , and the last thing I was going to do was get out in the cold weather to go measure it .