How we measure

How do you get width and height from the diagonal?

For an a:b screen, width = diagonal × a ÷ √(a² + b²) and height = diagonal × b ÷ √(a² + b²). A 55 inch (139.7 cm) 16:9 TV is 47.9 × 27.0 in (121.8 cm × 68.5 cm).

Ultrawide "21:9" panels are really 43:18, so we use that. A 34 inch (86.4 cm) ultrawide works out at 31.4 × 13.1 in.

Why do you compare screen area?

Area is width × height, and it shows how much picture you get. A 65 inch TV has 40% more area than a 55 inch TV, although its diagonal is only 18% longer.

How do you pick a TV size for a seating distance?

We recommend a screen that fills 30° to 40° of your view: 0.615 to 0.835 times your distance. From 10 ft (3.0 m) that is 74 to 100 in.

Viewing angle = 2 × arctan(half the screen width ÷ distance). A 65 inch TV seen from 10 ft fills 26.6° of your view.

How do you work out pixel density and sharpness?

Pixels per inch = √(width² + height²) in pixels ÷ the diagonal. A 27 inch (68.6 cm) 4K monitor has 163 PPI.

20/20 vision resolves about 1 arcminute, so pixels vanish beyond 3438 ÷ PPI inches. On a 65 inch 4K TV that is 4.2 ft (1.3 m).

Our Windows scaling suggestion is PPI ÷ 96, rounded to a 25% step between 100% and 300%. For that 27 inch 4K monitor it is 175%.

Where should a TV be mounted?

We center the screen at seated eye height, 42 in (107 cm) from the floor. The bottom edge of a 55 inch TV then sits 28.5 in (72.4 cm) up and the top edge 55.5 in.

How does the bank card calibration work?

Bank cards follow the ID-1 standard, 85.60 × 53.98 mm (3.37 × 2.13 in). When the outline matches the card, we know how many CSS pixels fill one millimeter.

An outline of 323 px on a screen that reports 1440 × 900 gives 95.8 CSS px per inch. The diagonal is then 17.7 in (45.0 cm), and at a pixel ratio of 2 the panel has 192 PPI.

What do Measured, Likely and Typical mean?

Browsers report a screen's pixels, never its size in inches. The home page labels each size it shows, so you can tell a measurement from an estimate.

Measured means you matched a bank card on this visit. Only a measured size draws the to-scale outlines elsewhere on the site.

Likely appears on iPhones, iPads and Macs. Their CSS screen size and pixel ratio point to one screen size, taken from Apple's specs and Xcode's simulator profiles.

A Mac at a pixel ratio of 2 shows half its native pixels each way, so a 3024 × 1964 MacBook Pro 14 reports 1512 × 982. If that size fits screens of different sizes, we show no Likely size.

Typical appears on other laptops and desktops, as a sentence rather than a number. We group maker spec sheets by resolution and give the narrowest range that holds 70% of them.

A range needs at least 30 laptop panels or 15 monitors. At 1920 × 1080, laptops are usually 14 to 15.6 in and monitors are usually 23.8 to 27 in.

How is the refresh rate measured?

We time 120 animation frames and take the median gap, which ignores the odd slow frame. A reading within 6% of a common rate snaps to it, so 143.9 frames per second shows as 144 Hz.

How are phone screen sizes worked out?

Makers publish the diagonal and the resolution, not the width. We scale the resolution to the diagonal, so a 6.1 inch (15.5 cm) phone at 1179 × 2556 is 2.6 × 5.5 in.

Where do model measurements come from?

Model sizes, weights and VESA patterns come from each maker's published spec sheet. Every row links its source and the date we checked it, and pages without enough sourced models are kept out of search results.

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