Screen Size Calculator: Inches to Width & Height in cm

A screen size calculator turns a diagonal in inches into real width and height, in centimetres and inches. It also runs the other way. Screen size itself is always the diagonal, and one inch is 2.54 cm. Width and height then follow from the aspect ratio, which is usually 16:9 on a television. Type in the inches and you get exact dimensions, screen area and a recommended viewing distance. So at 16:9 the whole conversion is two constants. First, width is the diagonal × 0.8716.

Second, height is the diagonal × 0.4903. So a 55 inch screen is 139.7 cm along its diagonal. It measures 121.8 cm wide and 68.5 cm high, or 47.9 × 27.0 inches and 0.83 m² of picture. Every figure on this page, however, describes the active display area. The bezel usually adds 0.5 to 2 cm per side, and it sits outside those numbers. Conversely, enter a width and a height in centimetres. It then returns the diagonal in inches and the nearest standard size.

How do I calculate screen width and height from the diagonal?

Width is the diagonal × 0.8716 and height is the diagonal × 0.4903 at 16:9. First convert the inches to centimetres, at 2.54 cm per inch. The advertised inch figure is only the diagonal of the active display area, though. On its own, therefore, it cannot tell you whether a set fits a cabinet, an alcove or a signage enclosure. Width and height can, although both of them change with the aspect ratio. This is the arithmetic the screen size calculator above runs:

1. Convert the diagonal to centimetres: inches × 2.54.
2. Width: diagonal × 16 ÷ √(16² + 9²). For 16:9 the factor is 0.8716.
3. Height: diagonal × 9 ÷ √(16² + 9²), a factor of 0.4903.

Example, a 55 inch 16:9 TV: 55 × 2.54 = 139.7 cm diagonal. Width: 139.7 × 0.8716 = 121.8 cm (47.9 in). Height: 139.7 × 0.4903 = 68.5 cm (27.0 in). Area: 0.83 m² (8.98 sq ft). The same diagonal at 16:10 instead gives 118.5 × 74.0 cm. At 21:9 it gives a width of 128.4 cm. The calculator above does this for any preset or custom ratio.

How big is a 55, 65 or 75 inch TV in cm?

55 inch TV dimensions

A 55 inch 16:9 TV measures 47.9 inches wide by 27.0 inches high, which is 121.8 × 68.5 cm. Its diagonal is 139.7 cm and its screen area is 0.83 m². The recommended viewing distance is 2.3 to 77.1 ft (0.7 to 23.5 m). Again, these are display-area figures. The bezel usually adds 0.2 to 0.8 in (0.5 to 2 cm) per side. So the body of most 55 inch models runs about 123 to 125 cm wide. The cabinet under it has to be wider still. It is, generally, the most common size for living rooms and mid-size meeting rooms. It is also the size the screen size calculator above opens on. Meanwhile, the same 55 inch diagonal at 16:10 gives a narrower, taller 118.5 × 74.0 cm. That is why a 55 inch monitor and a 55 inch TV are not interchangeable in a fixed enclosure.

65 inch TV dimensions

A 65 inch TV measures 56.7 inches wide by 31.9 inches high, which is 143.9 × 80.9 cm. Its diagonal is 165.1 cm and it holds 1.16 m². That is about 40% more area than a 55 inch set. Recommended viewing distance: 2.6 to 91.2 ft, or 0.8 to 27.8 m. First check that the width including the bezel fits your stand or alcove. That width is usually about 57.5 in, or 146 cm.

Most upgrades run out of room for the 22 cm of extra glass between a 55 and a 65. Still, only the diagonal is 65 inches. No edge of the panel is, and that is the most common misreading of a spec sheet. Across a 3 m meeting-room table, 65 inches reads easily from every seat. Its extra size buys impact rather than legibility. In a living room the step from 55 to 65 is the one most people notice. The step from 65 to 75, however, is the one most walls refuse.

75 inch TV dimensions

A 75 inch TV measures 65.4 inches wide by 36.8 inches high, which is 166.0 × 93.4 cm. Its diagonal is 190.5 cm and the picture covers 1.55 m². That is 86% more picture than a 55 inch set at the same 16:9 shape. Recommended viewing distance: 3.0 to 105.3 ft, or 0.9 to 32.1 m. This is boardroom, lobby or shop-window territory. Beyond 32.1 m, text gets too small, so consider 86 or 98 inches instead. Mounting also matters more here than at any smaller size. A 1.66 m span of glass certainly wants two studs or a solid wall. So confirm the bracket, the VESA pattern and the cable route before you order the panel. Sat closer than 3.0 ft, an HD panel this large starts to show its pixel structure on text. At 1.55 m² it also reads cleanly from the far end of a large lobby.

How far should I sit from the TV at each screen size?

Two limits set the range the screen size calculator shows for every diagonal. Pixel size sets the near end: the closest comfortable distance is about 1 m per mm of pixel pitch. Closer, your eye sees the pixels, a limit of visual acuity. Assuming an HD panel, bigger screens start further back. The far end comes from text size. In signage, the text that carries the message is usually about a fifth of the screen height, and it stays readable out to about 34 times the screen height. So a 55 inch screen reads clearly from 0.7 to 23.5 m. A bigger screen is never wrong, only more expensive: it simply reads from further away. The size table in the calculator above lists dimensions and the recommended viewing-distance range for 22 popular 16:9 sizes. Every row also carries its own anchor, so you can link straight to a single size.

Signage rule of thumb: for text to read clearly, allow capital letters of about 6 mm per metre of viewing distance. That is about 0.7 in per 10 ft. A 55 inch screen viewed from 77.1 ft needs letters of at least 5.38 in (13.7 cm). Similarly, a lobby screen viewed from 20 ft needs 1.4 in (3.5 cm) or more. The calculator also shows this value for every size.

Which screen size for digital signage or an LED wall?

In digital signage the viewing distance sets the smallest size that works, and the environment sets the display type:

• Up to 60 ft (counter, meeting room, checkout): 43 to 55 inches. Indoor screens at 350 to 500 nits are usually enough.
• 60 to 137 ft (lobby, hall, video wall): 65 to 98 inches. An LED screen is built from modules, so it reaches any width. An LED wall calculator therefore works from pixel pitch and viewing distance instead of a fixed diagonal.
• Shop window or outdoors: size by distance, but brightness matters most. Use 2,500 nits and up, on outdoor screens rated for rain and direct sun.

Take the exact figure from the screen size calculator above before you order the mount. In signage the enclosure, the recess or the pillar usually fails to fit, almost never the panel itself. Once the size is settled, content reaches the screen through a cloud digital signage system. Finally, design once, publish to every screen in one click, and swap the content remotely.

Screen size FAQ

Fitting a screen to the room

Updated: September 17, 2026 · Digital signage since 2009