Article Overview
A 1U chassis has a standard height of 1.75 inches (44.45 mm) and a width of 19 inches (482.6 mm), with mounting holes spaced according to EIA-310-D standards.
Standard Dimensions of a 1U Chassis
- Height: 1U = 1.75 inches (44.45 mm). Actual equipment height is slightly less, typically 1.72–1.745 inches (43.66–44.33 mm), to allow for airflow, thermal expansion, and safe insertion/removal .
- Width: The standard 19-inch rack width is measured from the outer edges of the mounting flanges. The usable interior width is approximately 17.75 inches (451 mm) due to flange thickness .
- Depth: Not standardized by the U system; 1U devices can range from 8 inches to 36 inches depending on the application, with typical servers around 24–28 inches and network switches 15–20 inches .
- Mounting Hole Spacing: 19-inch racks use uneven vertical spacing for mounting holes, typically three holes per U, allowing secure attachment of equipment . The horizontal spacing aligns with the 19-inch standard.
- Tolerance: Manufacturing tolerances are usually ±0.01 inches for precise fit .
Diagrammatic Representation
Front View (19-inch rack width)+-----------------------------------+ <- Top of 1U| || 1U Chassis | <- Height: 1.75" (44.45 mm)| |+-----------------------------------+ <- Bottom of 1U| Mounting Holes (3 per U) | <- Evenly spaced vertically+-----------------------------------+Side View (Depth varies by device)+-----------------------------------+ <- Front flange| || 1U Chassis | <- Depth: 8"–36" typical| |+-----------------------------------+ <- Rear flange
This diagram shows the height, width, and mounting hole positions for a standard 1U chassis. The front flanges align with the rack posts, and the depth varies depending on the device type. Clearance between units ensures proper airflow and prevents interference during installation .
Practical Considerations
- Airflow: Leave slight gaps between units for cooling.
- Compatibility: Ensure the chassis matches the rack's mounting thread type (e.g., square, threaded, or cage nut).
- Depth Check: Verify the rack depth accommodates the device, especially for deep servers or GPU-equipped 1U units.
By following these dimensions and tolerances, a 1U chassis will fit securely in a standard 19-inch rack, ensuring proper alignment and operational safety .
structure 1U – DATASHEET
Figure 2: Structure 1U – Side View Figure 3: Structure 1U – Top View (Z+) Figure 4: Structure 1U – Bottom View (Z-)
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