What is a 19 inch rack?

One of the first terms you’ll learn in the world of server is ‘19 inch rack’ because this is a standard that the industry revolves around. 19 inches refers to the mountable width of servers and the racks that they will be placed in. 

Since servers are housed in huge chunks of metal, adjustability is difficult. Generally, the racking process is easier if there is at least one aspect to the dimensions that remains the same.

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Why 19 inches? 

The standard was created by the Electronic Industries Alliance or EIA. This is the same group of people who standardized the term “rack unit” and other words used in the space today. 

EIA claims that the reasons for standardization is to “increase market share, boost quality levels and elevate customer satisfaction.” Though, it should be noted that EIA has no authority over the industry, other than their highly reputable recommendation. 

What does 19 inches refer to on a server rack? 

Rack Width
Rack Width Illustration

Ironically, 19 inches might not be the most important measurement when it comes to server rack width. At the end of the day, your rail needs to line up with the rack’s cage nuts or threaded holes.

To meet the 19 inch EIA standard, a server chassis width will need to be less than 17.75 inches. Any larger than this and you will not be able to insert the server through the front. Additionally, your rails or shelves needs threaded holes 18.31 inches apart. 

The front panel width, which refers to the actual panel of your server, is the only dimension that needs to be 19 inches. This measurement runs from essentially the outer edge of one square hole on the rack to the outside of a perpendicular square hole. 

Does server width matter? 

If you have a 19 inch rack and are worried about your server not fitting it, chances are you’ll be fine. Even though the 19 inch EIA standard isn’t a requirement, major brands like Intel, Dell, HP and IBM adhere to the standards on their servers. 

It is beneficial for companies to get on board with this standard so that they don’t lose customers over compatibility issues. Even Apple’s new rack mountable Mac Pro has a 19 inch width. 

Still, some servers are built bigger. In addition to 19 inch racks, you might come across 23 inch racks that are built for 23 inch servers. More space means more capability to increase performance so these are mostly tailored for data center environments. 

Other than that, there isn’t much to look out for in terms of server width. Dimensions like height and depth can vary much more than width, so it’s relieving to at least one standard for mounting. 

What are the best 19 inch server racks? 

The best server rack for you depends on a few factors

  • How much depth do you need? 
  • How much height do you need? 
  • How much space do you have? 

Height is measured by ‘rack units’, so a 1U server would be 1 rack unit or 1.75 inches. A simple way to gauge how much space you will need is to add up how many total rack units your equipment takes up, and then add a bit more space for expansion or accessories. 

Data Center Rack
Data Center Rack

Depth is relatively adjustable especially compared to height and width. This is because rails can adjust depth frontwards and backwards. Basically, as long as no equipment is over the capacity of the racks mounting depth, you should be able to find a rail that will be compatible. 

Space limitations might be the first thing you need consider.

  • The smallest racks you will find can fit on or under a desk, be mounted on a wall or ceiling, or turn a single server into a computer-like tower. 
  • Average sized racks will be around 42U in height, have 4 posts and could fit in a medium sized closet. These are typically used for businesses or schools that need a centralized location to transfer data. 
  • Larger racks won’t be too much taller than those mentioned previously, but might have more depth, room for fans, or just features in general. For instance, RackSolutions’ Data Center Rack starts with a height of 42U, but has a very high load capacity, locks, is designed to combat airflow circulation and has a significant amount of depth.


19 inch rack and rack unit



Why do most server racks have a 19 inch width?
Article Name
Why do most server racks have a 19 inch width?
A 19 inch width is standard for servers and the racks that mount them. Learn how the EIA came to this conclusion and how it helps.
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19 inch rack