Calculate screen size - how it works

You can easily calculate the screen diagonal of your TV or monitor. We show you how it works.

Calculate the screen size of the monitor or TV

1. To calculate the screen diagonal of your device, you only need the height and width of the screen. You can easily measure these using a scale or other measuring equipment. You should use the unit centimeters.
2. You can then calculate the diagonal using the "Pythagorean theorem". The mathematical formula is "a² + b² = c²". "A" and "b" are the latitude and longitude dimensions that you measured beforehand.
3. For example, if your screen is 65 cm wide and 45 cm high, the formula is: "65² + 45² = c²" or "4225 + 2025 = c²". Now all you have to do is add the numbers "4225" and "2025" together and take the root of it. The end result is 79.1 cm. If you don't want to calculate that in your head, you can just use an online Pythagoras calculator.
4. Since most screen diagonals are given in inches and not in centimeters, you still have to convert the centimeters. Simply divide the result by the number 2.54. In our example it would be "79.1 / 2.54 = 31.12". The screen would have a screen size of 79.1 cm or 31.12 inches.
5. In the end, you can compensate for any measurement errors simply by rounding the result.

Tip: Read also how you can change the screen size or resolution under Windows.