19inch

19inch refers to the standard width for equipment designed to be mounted in a 19-inch rack, a widely used framework in data centers, telecommunications, and professional audio-visual facilities. The term is often written as 19-inch or 19in. Equipment built for this format has mounting flanges or ears that align with the two vertical rack rails, enabling secure, interchangeable installation across manufacturers.

The defining dimension is the width between the inside faces of the mounting rails, which is 19 inches (approximately 482.6 mm). Vertical space in racks is measured in rack units (U), with 1U equal to 1.75 inches (44.45 mm). This unit-based system allows different devices to occupy standardized heights within the same rack, from 1U up to many tens of units.

Standards governing 19inch equipment and racks include ANSI/EIA-310, which specifies mounting hole patterns, tolerances, and other mechanical interfaces to ensure compatibility and interchangeability. The 19-inch format supports a broad range of equipment, including servers, storage devices, switches, patch panels, power distribution units, and many professional audio-visual devices. Racks come as open-frame structures, wall-mount enclosures, or fully enclosed cabinets, and vary in depth and load capacity to accommodate different installations and cooling requirements.

While 19inch is the dominant rack width, there are variations and non-standard applications in some sectors. When selecting components, compatibility should be verified for rail spacing, mounting screw type (commonly 10-32 UNC or M6), and overall depth.