Rack Unit (U) Space Planner

Count the rack units your kit needs, including the gaps you forgot.

What you provide

Rack height(U)

Full-height racks are usually 42U or 47U. Wall cabinets are 6U to 18U.

1U servers

2U servers

Switches and routers

Patch panels

UPS height(U)

Anything else(U)

Airflow and cable management gaps(U)

Result

PASS

24U free in a 42U rack

Height is the easy constraint. The two that actually stop installations are depth and weight: short-depth wall cabinets will not take a full-length server no matter how many U are free, and a rack filled with disk shelves can pass what the floor is rated for. Check the door-to-door depth and the loaded weight before ordering.

Diagnostic telemetry

Rack height: 42U
Equipment: 16U
Airflow and cable gaps: 2U
Total occupied: 18U
Free: 24U
Filled: 43%

What this cannot tell you

Height arithmetic on what you enter. It does not know your equipment list or the rack in front of you.
Height is rarely the constraint that stops an installation. Depth, weight and cooling are, and none of them are calculated here.

Take this with you

Rack Unit (U) Space Planner on RunTheTests — free browser-based sysadmin tools, no sign-up.