Device pixel

A device pixel is the smallest physical display unit capable of displaying a full color independent of its neighbor. It is the smallest physical unit of a display (such as a monitor or mobile phone screen), also known as a hardware pixel or physical pixel. Each device pixel is an individual dot that composes the output of the display. Device pixels are fixed and do not scale based on the viewport or CSS.

A device pixel is density-dependent, varying based on the display resolution. The device-pixel-ratio is the ratio of the resolution in physical device pixels to the resolution in CSS pixels for the display. It usually differs from a CSS pixel, which is an absolute length defined as being exactly 1/96th of 1 CSS inch. Devices considered Hi-DPI have more than one device pixel per CSS pixel in the same physical area, while low-DPI devices have less than a 1-to-1 ratio.