This Online tool helps for website resolution test. you to find your high definition monitor/laptop/mobile or screen resolutions(calculator).
Find out quickly for 100% free!, Online tool to find your screen resolution, The Screen resolution is frequently measured as width x height in pixels. For simple example about the resolution of 1366 x 768 means the 1366 pixels is width and 768 pixels is height of the screen.
Online Tool : whatismyscreenresolution