Why is my monitor's screen smaller than advertised?
Answer: So you bought a 17" monitor only to find that its screen is 15.75", measured diagonally. "This can't be right," you say, "I expected the screen to be 17". Well, unfortunately, this is normal for a CRT display. While the monitor's picture tube may be 17 inches, the actual "viewable area" may be less than 16 inches. This is because the screen does not use the entire tube for projecting the image.
By not using the full range of the monitor's cathode ray tube, the screen can display sharper edges and corners, which do not fade or bend around the sides of the screen. While this makes for a better screen image, it does pose the question of legitimate marketing. Shouldn't a 17" monitor have a 17" screen? I think so, but apparently display manufacturers do not. So, when buying a CRT display, don't just look at the screen size, but also check the viewable area, which will tell you exactly how much of the screen you can actually use. Also, make sure you check the monitor's dot pitch (lower is better) and its maximum resolution (higher is better).
LCD or flat screen displays, don't have the screen size issue that CRT monitors do. View this article for more information.