Display size

For the number of pixels measured vertically and horizontally per screen, see Display resolution.

File:LCD screen sizes.svg

Comparison of screen sizes by width, height, diagonal, area, and aspect ratio.

On 2D 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, usually in inches. 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

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", 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

File: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 (15:10)				8:5 (16:10)				5:3 (15:9)				16:9 (4²:3²)				21.3:9 (4³:3³)
(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)		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		8	3	28
3.7	9		7	6	43		8	6	42		8	5	41		8	5	40		8	5	39		8	5	38		9	4	32
4	10		8	6	50		8	6	50		8	6	48		9	5	46		9	5	46		9	5	44		9	4	37
4.3	11		9	7	58		9	7	57		9	6	55		9	6	54		9	6	53		10	5	51		10	4	43
5	13		10	8	79		10	8	77		11	7	74		11	7	72		11	7	71		11	6	69		12	5	58
7	18		14	11	154		14	11	152		15	10	146		15	9	142		15	9	139		15	9	135		16	7	113
10	25		20	16	315		20	15	310		21	14	298		22	13	290		22	13	285		22	12	276		23	10	231
11.6	29		23	18	423		24	18	417		25	16	401		25	16	390		25	15	383		26	14	371		27	11	311
13.3	34		26	21	557		27	20	548		28	19	527		29	18	513		29	17	503		29	17	488		31	13	409
14	36		28	22	617		28	21	607		30	20	584		30	19	568		30	18	558		31	17	540		33	14	453
15	38		30	24	708		30	23	697		32	21	670		32	20	652		33	20	640		33	19	620		35	15	520
15.4	39		31	24	746		31	23	734		33	22	706		33	21	688		34	20	675		34	19	654		36	15	548
17	43		34	27	910		35	26	895		36	24	861		37	23	838		37	22	823		38	21	797		40	17	668
18.5	47		37	29	1,077		38	28	1,060		39	26	1,019		40	25	992		40	24	974		41	23	944		43	18	791
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		44	19	834
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		47	20	924
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		49	21	1,019
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		51	22	1,118
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		54	23	1,222
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		56	24	1,331
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		59	25	1,444
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		61	26	1,562
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		63	27	1,684
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		66	28	1,811
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		68	29	1,943
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		70	30	2,079
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		73	31	2,220
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		75	32	2,366
34	86		67	54	3,638		69	52	3,580		72	48	3,442		73	46	3,352		74	44	3,290		75	42	3,187		80	34	2,671
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		91	39	3,514
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		98	41	4,076
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		108	45	4,889
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		112	47	5,323
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		117	49	5,776
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		129	54	6,989
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		136	57	7,773
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		140	59	8,318
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		150	63	9,464
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		164	69	11,322
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		187	79	14,787
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		197	83	16,303
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		232	98	22,646
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		239	101	24,039
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		253	107	26,950
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		260	110	28,468
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		356	150	53,383

History

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, the external diameter of the bulb was used to describe their size. Since these circular tubes were used to display 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 casing and 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 was universally 4:3. In the US, when virtually all 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 displays 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 display.

When the common aspect ratio went 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 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. 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, 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

• Display resolution
• Computer display standard