How to measure mobile cell phone screen size
The screen size of mobile cell phones is given as the diagonal measurement of the phones screen. When the size of a mobile phone is in pixels, then it is the measurement of the phone screen size in pixels of the sides of the phone screen, the width and height of the mobile phone in pixels and is called 'Resolution'.
The diagram of a phone here shows the smartphone screen dimensions in centimeters and inches. The phone screen is in light blue color and the screen size is the diagonal distance from the top or bottom corner to the opposite corner at the bottom or top of the screen
The screen sizes of smartphones are normally published in inches, but in many countries following the metric system, like Europe and India, mobile phone screen sizes are also specified in centimeters. To convert inches into Centimeters multiply the inch value by 2.54 (1 inch =2.54 cms or centimeters). To make screen size in inches from centimeters, divide by 2.54.
In the smartphone screen image here, the screen size is marked as 10.2 cms or 4 inches which is the measurement from the bottom left corner to the top right corner. Smartphone screen sizes can be specified in two different ways: one by the screen diagonal measurement in inches and, two: by the pixel count on the two sides of the phone screen, that is the width and height of the phone screen.
The pixel density or PPi of a phone screen depends on phone screen size in inches and the pixel measurement of the phone screen. More on this from our page about smartphone pixel density PPi
Pixel size of smartphone screens, mobile phone screen sizes pixels
The screen pixel size of smartphones is the number of pixels in the x-axis by the number of pixels in the y-axis. In the picture on this page, the mobile smartphone screen size in pixels is 720x1080.
The number of pixels along the 'X' axis or horizontally is shown as 720 pixels and along the 'Y' axis or height is shown as 1080 pixels. This is the orientation of the 'X' and 'Y' axis when the phone is held vertically. When the phone is viewed held horizontally the wider width of phone screen becomes the X-axis and the shorter height of screen becomes the Y-axis, when the smartphone resolution is 1080x720.
More on smartphone screen resolution and pixels are given in our page on 'Resolution'
Smartphone maximum screen size, Common Standard Screen size of smartphones
Common Standard Screen size of smartphones now average between 4 to 5.5 inches. The iPhone 6 and iPhone 6+ have a screen sizes of 4.7 and 5.5 inches respectively. The New Samsung Galaxy S7 has a screen size of 5.1 inches diagonally and the Samsung Note-5 has diagonal screen size of 5.7 inches. There are also popular phones with 6 inch screen sizes like the Google Nexus 6 and Lumia 1520. The maximum size of a smartphone screen now is 6 inches. Smartphones with over 5.5 inch screens are called 'Phablet' - a cross between a phone and a tablet .