TV Size Calculator

Diagonal, inches

Aspect ratio

Result

Diagonal, cm139.7
Width, cm121.8
Height, cm68.5
Screen area, m²0.834
Sit from, m1.68
Sit up to, m3.49

Diagonals in, dimensions out

Screen width, height and area from a diagonal in inches, plus the comfortable viewing distance range.

Televisions are sold by diagonal in inches while walls and cabinets are measured across in centimetres. To know whether a 65-inch set fits an alcove you need the width, not the diagonal — at 16:9 it is about 87 percent of it.

The second question is how far away to sit. General viewing suggests one and a half to two and a half diagonals; cinema viewing can go closer, to about 1.2. Sit too close to a 4K panel and pixels become visible, and on Full HD sooner still.

What this calculator shows

Diagonal in centimetres alongside screen width and height
Screen area, which is the honest way to compare two sizes
A comfortable range of viewing distances

What to keep in mind

Dimensions are for the screen itself; the bezel adds one to three centimetres per side.
One inch is exactly 2.54 centimetres — a definition, not a rounding.

FAQs

How many centimetres is a 65-inch TV?

165.1 cm on the diagonal, about 144 cm wide and 81 cm tall. It fits a 150 cm alcove, but only just once the bezel is counted.

How far should I sit?

1.2 to 2 diagonals for 4K, 2 to 2.5 for Full HD. Higher resolution allows closer seating without the pixel structure showing.

Why does area grow faster than the diagonal?

Because both dimensions grow together. An eighteen percent larger diagonal gives forty percent more area, which is why the step from 55 to 65 inches feels bigger than the numbers suggest.

How high should a TV be mounted?

Screen centre at seated eye level, usually 100 to 110 cm from the floor. Mounted higher, it forces the head back and tires the neck.

Worked example

A 55-inch television

Input: 55 inches, 16:9

Output: 139.7 cm diagonal, 121.8 cm wide, 68.5 cm tall

Note: Comfortable from 1.7 to 3.5 metres. Screen area is 0.83 m²; a 65-inch reaches 1.16 m² — forty percent more picture for an eighteen percent bigger number.

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TV Size Calculator

Result

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