To determine the length and width of a 2.5-inch screen, you must also know the resolution of the screen, that is, the length-width ratio of the screen. Commonly used screen aspect ratios are 4: 3 and 16: 9 (or variants 15: 9 and 16: 10), which can be obtained by Pythagorean theorem:
The length and width of the 4: 3 screen are 5.08cm and 3.8 1cm, respectively.
16: 9 The screen length and width are 5.54cm and 3. 1 1cm respectively.