You'll get the precise, standardized dimensions of a 1U server rack unit — including height (1. 45 mm), width (19″ / 48. 26 cm), mounting hole spacing, and critical clearance allowances — plus actionable guidance on verifying physical fit, avoiding common installation. A rack unit (abbreviated U or RU) is a unit of measure defined as 13⁄4 inches (44. It is most frequently used as a measurement of the overall height of 19-inch and 23-inch rack frames, as well as the height of equipment that mounts in these frames, whereby the height of the frame or. dimensions, mounting interf th a typical depth r structural topology accommodates (hot-swappable AC/DC l cycling. There are two 1U standards: Intellijel and Pulp Logic. The PCB behind the front panel is typically about 18.