Knowing the inches of your monitor is quite simple and there are many ways to know, the easiest way to find out this information is by looking for the monitor model on the hardware manufacturer’s page.
If you want to know how to calculate the inches of a monitor or you can not figure out the size using the previous method then what you have to do is measure the screen length diagonally, it would look like the next image:
It is verified in this way because it is evaluated with the width and height and thus an exact data is obtained. This measurement can be done with a measuring tape or with a ruler. Note that when measuring you can not measure the plastic or border around, bone, only the screen should be measured, this is the same for LCD, LED and CRT monitors.
It should be noted that the screen resolution is not the same as the size of the screen since many people believe that these two parameters refer to the same and it is not, the screen resolution is the number of pixels displayed on a screen. For example, I can have a monitor with a size of 22 inches with a screen resolution at 1920 × 1080.
The screen resolution of your computer can be checked in Control Panel-> Adjust screen resolution, which you can check there. The screen resolution you can have will depend a lot on the graphics card that has your PC either integrated or adapted.