To know the measurements of a 21-inch television we must know the aspect ratio of the screen. Currently, the vast majority of televisions in production have a 16: 9 aspect ratio. This means that if we divide the height of the screen by its width, the value obtained is equal to 16: 9, that is, approximately 1.78.
The aspect ratio can be known from the characteristics of the television . Today’s televisions with HD, full HD, and Ultra HD (also known as UHD or 4K) resolutions generally have a 16: 9 aspect ratio.
Older TVs with standard SD (Standard Definition) resolution have a 4: 3 aspect ratio. However, this type of format has been abandoned to make way for high definition with a 16: 9 aspect ratio.
21 inches refers to the length of the screen’s diagonal. If we express this length in centimeters, it equals 53.3 cm.
Assuming the aspect ratio is 16: 9, then the width of the screen is 46.5 cm and the height is 26.2 cm.
The image below shows the measurements for a 21-inch TV with a 16: 9 aspect ratio.
A few years ago, before the introduction of high definition displays (HD, Full HD and Ultra HD), the most common televisions had a 4: 3 aspect ratio. That is, the width was 1.33 times the height.
With this aspect ratio, a 21-inch TV would equal 42.7 cm in width and 32.0 cm in height as shown in the following image. Even so, today it is rare to find this type of television with a high number of inches.
These measurements indicate the dimensions of the screen only. Keep in mind that the total size of the TV will be slightly larger due to the frame that supports the screen. In addition, the depth of the television must be taken into account, which may vary depending on the model.