A “55-inch TV” sounds big, but how wide is it really, and will it fit on your wall? Screen sizes are always given as the diagonal in inches, which makes them hard to picture. This guide converts common TV and phone screen sizes to centimetres, explains width and height, and uses our CM to Inches Converter converter for any other size.
How screen size is measured
Screen size is the diagonal distance from one corner of the visible screen to the opposite corner. It does not include the frame (bezel) or stand.
Common TV sizes
For a standard 16:9 widescreen TV:
| Size | Diagonal | Width (approx.) | Height (approx.) |
|---|---|---|---|
| 32 in | 81 cm | 71 cm | 40 cm |
| 43 in | 109 cm | 95 cm | 54 cm |
| 50 in | 127 cm | 111 cm | 62 cm |
| 55 in | 140 cm | 122 cm | 68 cm |
| 65 in | 165 cm | 144 cm | 81 cm |
| 75 in | 191 cm | 166 cm | 93 cm |
Add a few centimetres for the frame when checking wall or cabinet space.
How to calculate width and height
For a 16:9 screen:
- Width ≈ diagonal × 0.872
- Height ≈ diagonal × 0.490
A 55-inch TV: width = 55 × 0.872 = 48 in (122 cm); height = 55 × 0.49 = 27 in (68 cm).
Choosing a size for your room
A common guideline for full HD is a viewing distance of about 1.5 to 2.5 times the screen diagonal, and closer for 4K. For a 55-inch TV, that is roughly 2 to 3.5 metres. Measure your room in feet or metres; the Feet to Meters converter helps if your tape shows feet.
Phone screens
Phones are also measured diagonally. A 6.7-inch phone screen is 17 cm diagonally. Because modern phones are tall and narrow (around 19.5:9 or 20:9), their width is much smaller than a TV of the same diagonal ratio would suggest.
Monitors and laptops
A 24-inch monitor is about 61 cm diagonally, and a 15.6-inch laptop screen about 39.6 cm. Ultra-wide monitors (21:9) are wider and shorter than standard ones of the same diagonal.
Before you buy
- Measure the space, including room for ventilation.
- Check the TV’s full dimensions in the specification sheet, often in cm or mm.
- Convert as needed and compare. For box sizes during delivery, the packaging is bigger still.
For the basic conversion method, see how to convert cm to inches.
Projectors and wall space
If you are choosing between a large TV and a projector, measure the wall in centimetres and convert the image size you want. A 100-inch projected image (16:9) is about 221 cm wide and 125 cm tall, so it needs a large clear wall. Room dimensions in feet can be converted with the Feet to CM Converter converter.
Frequently asked questions
How is TV size measured?
Diagonally across the visible screen, in inches.
How wide is a 55-inch TV?
About 122 cm (48 inches) for a 16:9 screen, plus the frame.
How many cm is a 6.5-inch phone screen?
About 16.5 cm diagonally.