21inch

21inch refers to a measurement used to describe the diagonal size of a screen or display. In display technology, the size is typically defined by the diagonal length of the active viewing area, and 21 inches equals about 53.34 centimeters.

Historically, 21-inch displays were common for computer monitors and television sets. Many early CRT monitors used a 4:3 aspect ratio and presented a compact, mid-size option for desktops. As flat-panel technology evolved, 21-inch screens continued to appear, though the market gradually shifted toward larger and widescreen formats.

In contemporary products, 21-inch class displays are still available, often marketed as around 21.5 inches or described by nominal size rather than an exact diagonal. Modern variants tend to favor widescreen aspect ratios such as 16:9 or 16:10, with resolutions ranging from Full HD (approximately 1920x1080) to higher pixel densities depending on the model. The exact resolution and pixel density vary by manufacturer and panel type.

Usage of the term 21inch is more common in model naming and informal references than as a standardized category. When selecting a screen, buyers typically consider the diagonal size alongside resolution, panel type, color accuracy, refresh rate, and input options to ensure the display meets their needs.