What Is My Screen Resolution

Why there are two resolutions

A screen has its native resolution, the number of pixels in the matrix, and a size in CSS pixels that websites use. On a regular monitor the two are the same. On Retina screens, and in Windows at 125 or 150% scaling, the system draws each CSS pixel with several physical pixels, so websites see a smaller number: on a 2880 × 1800 screen that is 1440 × 900.

The large number on this page is the native resolution. You compare it with your monitor's specifications, and use it to pick wallpapers and game settings. The size in CSS pixels matters when you build websites.

Browser window and the available area

The available area is the screen without the taskbar and Dock. The browser window shows the visible part of the page: media queries fire based on its width. The values update on their own when you resize the window, move it to another monitor, or rotate your phone.

Pixel density

Resolution alone does not tell you how sharp a screen is. Enter the diagonal, and the page will calculate PPI from the native resolution. For print and other people's screens there is a separate PPI / DPI calculator.