Server Rack Sizes: Rack Units, Depth and 42U
Rack height is counted in rack units (U) of 1.75 inches, the standard rack is 19 inches wide, and 42U is the common full-height cabinet; depth varies.
By Paul SyversonFounder.
On this page
The short answer
Server racks are sized on three numbers:
- Height in rack units (U). One U is 1.75 inches (44.45 mm). A 42U rack holds 42 of those units stacked.
- Width. The common standard is the 19-inch rack: equipment panels, including their mounting ears, are 19 inches (482.6 mm) wide.
- Depth. This is not fixed by the standard. Four-post racks are often 600 mm, 800 mm or 1,010 mm deep, but it varies by maker.
Count the U of every device you plan to mount, add room to grow, then check the rack is deep enough for your longest device.
What a rack unit means
The rack unit comes from the EIA-310 standard (also published as IEC 60297 and DIN 41494). Mounting holes on the rails repeat in a pattern every 1.75 inches, so every device lines up with the holes no matter where it sits.
A device's front panel is a little shorter than its U count suggests. A 1U panel is 1.719 inches tall rather than 1.75, which leaves a small gap so gear can slide in and out without binding. Rails between the posts leave 17.75 inches (450.85 mm) of open width for the equipment body.
Common rack heights
| Height | Mounting space | Racks on Wiki Shopping |
|---|---|---|
| 1U | 1.75 in | 60 |
| 2U | 3.5 in | 31 |
| 4U | 7 in | 33 |
| 6U | 10.5 in | 32 |
| 8U | 14 in | 32 |
| 12U | 21 in | 78 |
| 22U | 38.5 in | 18 |
| 42U | 73.5 in | 80 |
| 44U | 77 in | 14 |
The mounting space column is simply the U count times 1.75 inches. The frame itself is taller than its mounting space, so check the maker's outside dimensions before buying for a room with a low ceiling or a narrow door.
A standard 19-inch server cabinet is typically 42U tall, 600 mm (24 in) wide and 36 inches deep. Cabinets are generally kept no wider than a 24-inch floor tile.
Open frame vs enclosed, two-post vs four-post
- Open-frame racks cost less and keep gear easy to reach, but leave it exposed to dust.
- Enclosed cabinets add doors and side panels; models with fans and filters protect equipment from dust.
- Two-post racks have two uprights joined at the top and a wide foot. They are mostly used for telecom equipment.
- Four-post racks have mounting rails at the front and the back. Most data centers use them.
On Wiki Shopping, 100 racks are listed as open frame and 95 as enclosed cabinets. 49 are listed for wall mounting.
Other widths: 10-inch and 23-inch
A 10-inch rack keeps the same 1.75-inch unit but is narrower; it is used by some telecom and network gear and by hobbyists with little space. A 23-inch rack is wider and is used mainly for telephone equipment. On Wiki Shopping, 267 racks list a 19-inch rail width, 20 a 10-inch width and 9 a 23-inch width.
How we count
Height, rail width, rack type and wall mounting are read from each rack's store listing. Racks that do not state a value are left out of that count. The counts change as listings are added or removed.
Shop by spec
Server Racks
+Provides 16 rack spaces for a larger equipment setup
+Rack includes casters for easy movement
$140.02-65%List: $399.99
as of 11/04/2026 11:05 PST - DetailsProduct details
Pros
+Provides 16 rack spaces for a larger equipment setup
+Rack includes casters for easy movement
How pros and cons are picked (About: Disclaimer)Other stores (1)
ReverbVisit store
About this product
- Solid steel and feature fully enclosed steel side panels
- Features 4 heavy-duty, 3 inch casters with locking fronts
- Each rack includes a single-space flanged blank panel
- Unique steel support bar construction allows for Metric or US threads
- Available in four sizes to accommodate any rackmounted gear setup: 8-space, 12-space, 16-space and 21-space
16 Height
+16U capacity for a large equipment load
+Front and rear rail access for easy wiring
+21.5-inch rackable depth fits deep gear
−Large case is heavy to move without casters
$731.94-14%Was: $849.99
as of 11/04/2026 02:09 PST - DetailsProduct details
$731.94as of 11/04/2026 02:09 PST - Details
View on AmazonPros
+16U capacity for a large equipment load
+Front and rear rail access for easy wiring
+21.5-inch rackable depth fits deep gear
+Rack casters allow the case to be moved
Cons−Large case is heavy to move without casters
How pros and cons are picked (About: Disclaimer)About this product
- RUGGED PLYWOOD CONSTRUCTION: Built from 9mm plywood with a tough laminated exterior for long-lasting durability on the road.
- COMMERCIAL-GRADE HARDWARE: Features heavy-duty plated hardware, reinforced ball corners, tongue-and-groove aluminum valance, and 3.2mm thick front and rear rack rails.
- SECURE HANDLING & ACCESS: Equipped with red recessed twist latches and spring-loaded rubber-gripped handles for easy, reliable operation.
- MOBILITY WITH LOCKING CASTERS: Includes four fixed 4″ heavy-duty casters, two of which lock for added stability during setup and transport.
- DESIGNED AND SUPPORTED IN THE USA: Proudly developed and backed by our team in Tampa, Florida, ensuring quality craftsmanship and responsive customer support.
12 Height
+12U capacity for a mid-sized rig
+Built-in casters for moving the case around
+Designed as a DJ road rack for touring use
−Load rating of 61 lb limits heavy gear
$319.99-14%List: $369.99
as of 11/04/2026 02:09 PST - DetailsProduct details
$319.99as of 11/04/2026 02:09 PST - Details
View on AmazonPros
+12U capacity for a mid-sized rig
+Built-in casters for moving the case around
+Designed as a DJ road rack for touring use
+Rated to hold up to 61 lb of equipment
Cons−Load rating of 61 lb limits heavy gear
Compared with this page−61lb load capacity: 177 of the 196 here have a higher load capacity
How pros and cons are picked (About: Disclaimer)Other stores (1)
ReverbVisit store
About this product
- Model # SA-PTR-12UC | 12 Space Rack with Heavy Duty 4" Casters | Standard 19" Mounting Rail Width | Heavy duty and ready for abuse | Black with aluminum rails
- 3/8" plywood Construction | Lightweight, Pro design | Front and rear removable doors | Has dual 4" steel link locks on both doors
- Dual spring handles on each side | 4 steel L brackets added for strength per side | Very well braced | Steel rack rails - Front and rear rack rails | Weight: 61.3 lbs
- Outer Dimensions with Doors On: Height: 29" with Casters - 23" Without | Width: 21" - Depth: 26"
- Inside Dimensions: Rail to Back with Rear Door On: 20 1/2" | Rail to Rear Edge of Case with Door Off: 18 1/2" | Front Rail to Rear Rail: 17 1/2"
+Mounted on casters for rolling the rack around
+Rated to hold up to 75 lb of mixer or DJ gear
+Standing rack design for mixers and DJ equipment
−Lower 75 lb load rating than the other studio stands
$69.95-13%List: $79.95
as of 11/04/2026 02:09 PST - DetailsProduct details
$69.95as of 11/04/2026 02:09 PST - Details
View on AmazonPros
+Mounted on casters for rolling the rack around
+Rated to hold up to 75 lb of mixer or DJ gear
+Standing rack design for mixers and DJ equipment
Cons−Lower 75 lb load rating than the other studio stands
Compared with this page−75lb load capacity: 175 of the 196 here have a higher load capacity
How pros and cons are picked (About: Disclaimer)Other stores (1)
ReverbVisit store
About this product
- SECURE YOUR MIXER AUDIO GEAR: Protect your studio remote units, digital or analog multi-track recorders, midi data input devices, auto locators, drum machines, turntables, and mixers with this premium quality rolling stand. Whether for home, on stage, or in your professional studio, this portable DJ cart will fit all devices sized at 15.5 inches x 38 inches W and 22 inches L, while the padded mounting platform will keep them firmly in place and safe at all times.
- MOVE AROUND OR LOCK IN PLACE YOUR MIXING TABLE: The 4 detachable casters (2 of them equipped with a locking option) make the stand easy to move around from place to place or lock when you want it to stay put. Can also be used as a drum music stand that rolls in and out next to a drummer. A must-have for portable studios, this rolling rack mount audio mixer stand also features special rubber feet that offer increased stability when the casters are removed.
- HEAVY DUTY, ALL STEEL CONSTRUCTION MUSIC TABLE: Designed to safely hold your audio recording devices, studio gear, and digital music equipment, while keeping it easily accessible, this all-steel standing rack boasts two (2) heavy-duty, lock-and-pin adjusting systems: Select your preferred height (from 27.5" to 37") by adjusting the base support post or position the tilting mount platform in the best angle to suit your needs.
- TILTING TOP MOUNTING PLATFORM TO GET PERFERCT ANGLE: Its extremely durable construction and sleek design make this rolling studio mixer stand the #1 choice for most music performers and audio professionals. The top mounting platform tilts at fixed angles to get your desired angle adjustment. Specs: Caster wheel size: 50mm x 17mm. Support base shaft: 1.375 inches x 1.375 inches. Leg spread area: 25.5 inches. Mounting platform: 16.875 inches W, 14 inches L. Weight capacity: 75 pounds.
- 1-YEAR WARRANTY – All products we sell from laptop stands, recording studio equipment, disc jockey accessories and dj stands, to stage equipment and stage lighting packages, and everything in between comes with our exclusive, 30-day money back return policy and a premium 1-year warranty! All you have to do is contact us within 30 days to request a return, or within 365 days from purchase to request a warranty replacement.