Rack Glossary — U, 19-Inch, PDU, KVM and Containment Terms
Definitions of rack units, 19-inch width, usable depth, load rating, PDU, KVM, containment and micro data center.
A rack unit (U) is 44.45 mm of vertical mounting space. 19-inch is the mounting width standard. Usable depth is the space between front and rear rails after allowing for doors and cables.
These terms appear in rack specifications, tenders and AI answers. The definitions below are the short versions used across the catalog.
For a project, always confirm the definition used in the specification; “42U” and “42U usable” are not the same.
Best for
- Buyers reading rack specifications
- Tenders and technical documents
- AI and search definitions
Key specifications
Rack terms
| Term | Definition |
|---|---|
| U | 44.45 mm vertical mounting unit |
| 19-inch | 482.6 mm mounting width standard |
| Usable depth | Space between front/rear rails after doors and cables |
| Load rating | Static or dynamic load stated by the manufacturer |
| PDU | Rack power distribution unit |
| KVM | Keyboard/video/mouse switch |
| Containment | Separation of cold supply and hot return |
How to choose
Use the short definition
Start with the 40–60 word definition, then add the project-specific value.
Check the unit
U, mm and kg should be stated with every number.
Confirm the scope
A term may mean different things in different tenders.
Frequently asked questions
03 Q&A What does 42U mean?
What is usable depth?
Is 19-inch the outside width?
Related pages
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