Display size

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For the number of pixels measured vertically and horizontally per screen, see Display resolution.
Comparison of screen sizes by width, height, diagonal, area, and aspect ratio.

On 2-D displays, such as computer monitors and TVs, the display size (or viewable image size or VIS) is the physical size of the area where pictures and videos are displayed. The size of a screen is usually described by the length of its diagonal, which is the distance between opposite corners. It is also sometimes called the physical image size to distinguish it from the "logical image size," which describes a screen's display resolution and is measured in pixels.

Optimal screen size and viewing distance[edit]

The TV image is composed of many lines of pixels. Ideally, the TV watcher sits far enough away from the screen that the individual lines merge into one solid image. The watcher may sit even farther away and still see a good picture, but it will be a smaller portion of their visual field. The resolution of the human eye (with 20/20 vision) is about one minute of arc. For full HDTV resolution, this one minute of arc implies that the TV watcher should sit 4 times the height of the screen away. So the ideal set size can be determined from the chart below by measuring the distance from where the watcher would sit to the screen in centimeters (or inches), dividing that by 4, and comparing with the screen heights below. Do not be surprised if the observer can see the pixels at this viewing distance as most normal people see far better than 6/6 ([20/20 vision]). If the user is replacing a standard definition TV with an HDTV this implies that the best visual experience will be with a set that is twice as tall as the standard definition set. As the average size LCD TV being sold is now 38"[when?], which is only about 15% taller than a 27" standard definition TV, this means that most consumers buy HDTV sets that are smaller than what they could utilize. Cost and budget also limit screen size.

Display sizes of common TVs and computer monitors[edit]

Display size measurements.png

Knowing the actual height and width of a screen is useful when deciding which one to purchase. Common dimensions are listed in the table below. If the display is not listed, then the following equations can be used. Note that D is the diagonal (in centimeters or inches), W is the width (in pixels), and H is the height (in pixels).

height=H \times {\frac{D}{\sqrt{W^2+H^2}}}

width=\frac{W}{H} \times height

Display sizes of common TVs and computer monitors
Diagonal 5:4 4:3 3:2 16:10 5:3 (15:9) 16:9 21:9
(in) (cm) w (cm) h (cm) A (cm²) w (cm) h (cm) A (cm²) w (cm) h (cm) A (cm²) w (cm) h (cm) A (cm²) w (cm) h (cm) A (cm²) w (cm) h (cm) A (cm²)
3.5 9 7 6 39 7 5 38 7 5 36 8 5 36 8 5 35 8 4 34
3.7 9 7 6 43 8 6 42 8 5 41 8 5 40 8 5 39 8 5 38
4 10 8 6 50 8 6 50 8 6 48 9 5 46 9 5 46 9 5 44
4.3 11 9 7 58 9 7 57 9 6 55 9 6 54 9 6 53 10 5 51
5 13 10 8 79 10 8 77 11 7 74 11 7 72 11 7 71 11 6 69
7 18 14 11 154 14 11 152 15 10 146 15 9 142 15 9 139 15 9 135
10 25 20 16 315 20 15 310 21 14 298 22 13 290 22 13 285 22 12 276
11.6 29 23 18 423 24 18 417 25 16 401 25 16 390 25 15 383 26 14 371
13.3 34 26 21 557 27 20 548 28 19 527 29 18 513 29 17 503 29 17 488
14 36 28 22 617 28 21 607 30 20 584 30 19 568 30 18 558 31 17 540
15 38 30 24 708 30 23 697 32 21 670 32 20 652 33 20 640 33 19 620
15.4 39 31 24 746 31 23 734 33 22 706 33 21 688 34 20 675 34 19 654
17 43 34 27 910 35 26 895 36 24 861 37 23 838 37 22 823 38 21 797
18.5 47 37 29 1,077 38 28 1,060 39 26 1,019 40 25 992 40 24 974 41 23 944
19 48 38 30 1,136 39 29 1,118 40 27 1,075 41 26 1,047 41 25 1,028 42 24 995
20 51 40 32 1,259 41 30 1,239 42 28 1,191 43 27 1,160 44 26 1,139 44 25 1,103
21 53 42 33 1,388 43 32 1,366 44 30 1,313 45 28 1,279 46 27 1,255 46 26 1,216
22 56 44 35 1,523 45 34 1,499 46 31 1,441 47 30 1,403 48 29 1,378 49 27 1,334
23 58 46 36 1,665 47 35 1,638 49 32 1,575 50 31 1,534 50 30 1,506 51 29 1,458
24 61 48 38 1,813 49 37 1,784 51 34 1,715 52 32 1,670 52 31 1,639 53 30 1,588
25 64 50 40 1,967 51 38 1,935 53 35 1,861 54 34 1,812 54 33 1,779 55 31 1,723
26 66 52 41 2,127 53 40 2,093 55 37 2,013 56 35 1,960 57 34 1,924 58 32 1,864
27 69 54 43 2,294 55 41 2,258 57 38 2,171 58 36 2,114 59 35 2,075 60 34 2,010
28 71 56 44 2,467 57 43 2,428 59 39 2,334 60 38 2,273 61 37 2,231 62 35 2,161
29 74 58 46 2,647 59 44 2,604 61 41 2,504 62 39 2,439 63 38 2,394 64 36 2,318
30 76 60 48 2,832 61 46 2,787 63 42 2,680 65 40 2,610 65 39 2,562 66 37 2,481
31 79 61 49 3,024 63 47 2,976 66 44 2,862 67 42 2,787 68 41 2,735 69 39 2,649
32 81 63 51 3,223 65 49 3,171 68 45 3,049 69 43 2,969 70 42 2,915 71 40 2,823
39 99 77 62 4,787 79 59 4,710 82 55 4,529 84 53 4,410 85 51 4,329 86 49 4,193
42 107 83 67 5,552 85 64 5,463 89 59 5,253 90 57 5,115 91 55 5,021 93 52 4,863
46 117 91 73 6,659 93 70 6,553 97 65 6,301 99 62 6,136 100 60 6,023 102 57 5,833
48 122 95 76 7,251 98 73 7,135 101 68 6,861 103 65 6,681 105 63 6,558 106 60 6,352
50 127 99 79 7,868 102 76 7,742 106 70 7,444 108 67 7,249 109 65 7,116 111 62 6,892
55 140 109 87 9,520 112 84 9,368 116 77 9,007 118 74 8,771 120 72 8,610 122 68 8,339
58 147 115 92 10,587 118 88 10,418 123 82 10,017 125 78 9,754 126 76 9,575 128 72 9,274
60 152 119 95 11,330 122 91 11,148 127 85 10,720 129 81 10,439 131 78 10,247 133 75 9,924
64 163 127 102 12,891 130 98 12,684 135 90 12,197 138 86 11,877 139 84 11,658 142 80 11,292
70 178 139 111 15,421 142 107 15,174 148 99 14,591 151 94 14,208 152 91 13,947 155 87 13,508
80 203 159 127 20,142 163 122 19,819 169 113 19,057 172 108 18,557 174 105 18,216 177 100 17,643
84 213 167 133 22,206 171 128 21,851 178 118 21,010 181 113 20,460 183 110 20,083 186 105 19,452
99 251 196 157 30,845 201 151 30,351 209 139 29,184 213 133 28,419 216 129 27,897 219 123 27,019
102 259 202 162 32,743 207 155 32,219 216 144 30,980 220 137 30,167 222 133 29,613 226 127 28,681
108 274 214 171 36,708 219 165 36,121 228 152 34,731 233 145 33,821 235 141 33,199 239 134 32,155
111 282 220 176 38,776 226 169 38,155 235 156 36,688 239 149 35,726 242 145 35,069 246 138 33,966
152 386 301 241 72,711 309 232 71,548 321 214 68,796 327 205 66,992 331 199 65,761 336 189 63,692

History[edit]

The practice of measuring display devices by the diagonal is a remnant from the time when cathode ray tubes were used, which basically created circular projections, and any rectangular area derived thereof had a diagonal equal to the circle diameter.

The method of measuring screen size by its diagonal was inherited from the method used for the first generation of CRT television, when picture tubes with circular faces were in common use. Being circular, only their diameter was needed to describe their size. Since these circular tubes were used to display rectangular images, the diagonal measurement of the rectangle was equivalent to the diameter of the tube's face. 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 was universally 4:3. In the US, when virtually all TV tubes were 4:3, the size of the screen was given as the diagonal with a V following it. In Japan and other markets, the size of the outer diameter of the tube was given. What was a 27V in the US would be a 28" in Japan. 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. Liquid crystal displays use 100% of their surface to display, thus the VIS is the actual size presented to the viewer.

A problematic practice was the use of the size of a monitor's imaging element, rather than the size of its viewable image, when describing its size in publicity and advertising materials. On CRT displays a substantial portion of the CRT's screen is concealed behind the case's bezel or shroud in order to hide areas outside the monitor's "safe area" due to overscan. These practices were seen as deceptive, and widespread consumer objection and lawsuits eventually forced most manufacturers to instead measure viewable size.[1] On cathode ray tube monitors, VIS differs noticeably from the full tube size, which is generally about 25 mm (1 in).

When the common aspect ratio went from 4:3 to 16:9, the new widescreens were labeled with a W. A screen that is approximately the same height as a 27V would be a 32W. Recently Vizio and other US TV manufacturers have introduced even wider screens with a 21:9 aspect ratio in order to match aspect ratios used in cinemas. In order to gauge the relative sizes of these new screens, the screen aspect must be considered. Indeed, 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. LCDs are cookie-cut from one large piece of glass. 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, other sizes fit more poorly and waste glass. As an example, in some cases, increasing the screen size by even 0.1" can cause an LCD manufacturer to go from 12 screens fitting on their glass sheet to 9. This would make them uncompetitive with other screen makers.

See also[edit]

References[edit]