A Rack Unit (U or RU) is the standard height measurement used for mounting equipment in server racks. 5 inches tall, a 4U device is 7 inches tall, and so on. This article explains definition, planning, installation tips, and trends. 45 mm), making it easy to size and organize hardware in a consistent, stackable way. Whether you're building a server setup or an energy storage. You'll instantly know how tall your server rack needs to be—and whether your gear will fit—once you understand that 1U = 1.
[PDF Version]