Editing Display size (section)

== History ==
The method of measuring screen size by its diagonal was inherited from the first generation of [[CRT projector|CRT]] televisions, which had [[Cathode-ray tube|picture tubes]] with circular faces. Being circular, the external [[diameter]] of the bulb was used to describe their size. Since these circular tubes displayed rectangular images, the diagonal measurement of the visible rectangle was smaller than the diameter of the tube due to the thickness of the glass surrounding the [[phosphor]] screen, which was hidden from the viewer by the [[Housing (engineering)|casing]] and [[Bezel (screen)|bezel]]. This method continued even when cathode ray tubes were manufactured as rounded rectangles. It had the advantage of being a single number specifying the size and was not confusing when the [[Aspect ratio (image)|aspect ratio]] was universally 4:3. In the [[United States|US]], when [[virtually]] all [[Cathode-ray tube|TV tubes]] were 4:3, the size of the screen was given as the true screen diagonal with a ‘V’ following it (this was a requirement in the US market but not elsewhere). In virtually all other markets, the size of the outer diameter of the tube was given. What was a 27V in the US could be a 28" elsewhere. However, the V terminology was frequently dropped in US [[advertising]] referring to a 27V as a 27". This was not misleading for the consumer as the seller had to give the actual screen size by law. [[Flat panel display]]s by contrast use the actual diagonal of their visible display size, thus the size is the actual size presented to the viewer in all markets. This means that a similarly specified size of display will be larger as a flat panel display compared with a [[Cathode-ray tube|cathode ray tube]] display.

When the common aspect ratio shifted from 4:3 to 16:9, the new widescreens were labeled with a W in the US. A screen that is approximately the same height as a 27V would be a 32W. [[Vizio]] and other US TV manufacturers have introduced even wider screens with a 21:9 aspect ratio to match aspect ratios used in [[Movie theater|cinemas]]. To gauge the relative sizes of these new screens, the screen aspect must be considered. In a commercial market where multiple aspect ratios are being sold, it will always take two numbers to describe the screen size, some combination of diagonal, aspect ratio, height or width.

Set sizes are frequently given as a ‘class’ as screens from different manufacturers will have slight differences in size. However, the "class" should be within 1/2" of the actual size. The reasons for the different sizes within a class stem from differences in the manufacturers' equipment. As manufacturers move from one size to another, newer larger sizes must fit on the same size glass, though with fewer displays being cut from it. Some sizes fit well and maximize glass utilization, while other sizes fit more poorly and waste glass. For example, in some cases, increasing the screen size by even 0.1” can cause an [[Liquid-crystal display|LCD]] manufacturer to go from 12 screens fitting on their glass sheet to 9.