# 19-inch rack units and mounting ears (EIA-310)

> What are 1U rack mount dimensions?

- Category: Hardware › Mounts
- Kind: Hardware
- Basis: EIA-310-D / IEC 60297: 19 in rack, 1U = 44.45 mm, hole spacing 15.875 / 15.875 / 12.7 mm, mounting rails 465.1 mm apart
- Page: https://xemstudio.com/objects/rack-19in-ears/ · JSON: https://xemstudio.com/api/geometry?object=rack-19in-ears · Plain text: https://xemstudio.com/objects/rack-19in-ears/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); linked files under their publishers' licenses

## Notes

- 1U = 44.45 mm (1.75 in). Equipment height is 1U minus about 0.8 mm so panels don't bind: a 1U faceplate is 43.6 mm tall; 2U is 88.1 mm.
- Hole pattern per U: 6.35 / 22.225 / 38.1 mm from the U boundary (15.875-15.875-12.7 repeating). Rail-to-rail inside width 450.85 mm; hole centres 465.1 mm apart; faceplate width 482.6 mm (19 in).
- Cage nuts take 9.5 mm square holes (M6 or 10-32 screws); threaded rails are usually 10-32 or M6.
- Files are ear test plates with the slot pattern for 1U and 2U.

## Sizes

| dimension | mm |
|---|---|
| 1U | 44.45 |
| 1U faceplate height | 43.6 |
| hole offsets within a U | 6.35, 22.225, 38.1 |
| rail hole centres (width) | 465.1 |
| inside rail width | 450.85 |
| faceplate width | 482.6 |
| cage nut square hole | 9.5 |

## Where the files are

- Wikipedia: [19-inch rack](https://en.wikipedia.org/wiki/19-inch_rack) — web — CC BY-SA 4.0 (text)
- Wikipedia: [Rack unit](https://en.wikipedia.org/wiki/Rack_unit) — web — CC BY-SA 4.0 (text)

## Free STEP/STL (2 parts, CC BY 4.0, Xem Studio)

Index: https://xemstudio.com/files/hardware/rack-19in-ears/index.json

- rack-ear-1u: [STEP](https://xemstudio.com/files/hardware/rack-19in-ears/rack-ear-1u.step) · [STL](https://xemstudio.com/files/hardware/rack-19in-ears/rack-ear-1u.stl) — 1U rack ear test plate: 44.45 mm per U, slots at 6.35 / 22.225 / 38.1
- rack-ear-2u: [STEP](https://xemstudio.com/files/hardware/rack-19in-ears/rack-ear-2u.step) · [STL](https://xemstudio.com/files/hardware/rack-19in-ears/rack-ear-2u.stl) — 2U rack ear test plate: 44.45 mm per U, slots at 6.35 / 22.225 / 38.1

## Questions

**How tall is 1U?**

44.45 mm (1.75 in). Make a 1U panel 43.6 mm so it clears the neighbours; 2U panels are 88.1 mm.

**What is the 19 inch rack hole spacing?**

Three holes per U at 6.35, 22.225 and 38.1 mm from the U boundary (gaps of 15.875, 15.875, 12.7 mm); the two rails' hole centres are 465.1 mm apart.

**What size are rack screws?**

10-32 in most US racks, M6 in most EU racks and with cage nuts; the cage-nut hole is 9.5 mm square.

## Fits with

- [VESA mount hole patterns: 75, 100, 200×100, 200×200, 400×200](https://xemstudio.com/objects/vesa-mount-patterns/)
- [Socket head cap screws, M2–M8 (ISO 4762 / DIN 912)](https://xemstudio.com/objects/socket-head-cap-screws-metric/)
- [Imperial machine screws: #4-40, #6-32, #8-32, 1/4-20](https://xemstudio.com/objects/imperial-machine-screws/)
- [Panel cutouts: IEC inlet, rockers, barrel jack, USB-C, HDMI, LEDs, Neutrik D](https://xemstudio.com/objects/panel-cutouts/)