All TV's are measured diagonally. Full Stop. All manufacturers do this regardless of the TV being 16:9, 4:3, CRT, LCD, LED, plasma, or any other relevant variable. The greater difference in the diagnol and width measurement on a 16:9 versus a 4:3 means more public awareness to the standard but also related misperceptions and falsehoods. Fun facts: 4:3 CRT or "tube" TV's are measured by tube size which is larger than the actual viewing area. TV's of today with 16:9 ratio are measured by the screen itself. Old standards left you expecting and receiving less as size was exaggerated when advertised. Now you can expect what you pull out on that first Netflix and chill night to be as advertised, every inch functional and enjoyable to bring hours of pleasure.