Free online rack space calculator to determine server rack U space requirements, equipment placement, and rack utilization. The rack doors may dictate how much space you need to get them all the way open (split doors like those on the SR42UB can reduce this a bit), but really being able to get your stuff in and out of the rack and ensuring safety when doing so is what matters. This calculator helps you plan rack layouts by calculating the total rack units. Before arranging data centers, you need to know the requirements for installing this type of network furniture. When spacing follows standardized measurements, it allows hardware from different. A cabinet or rack must belong to one of the following types: Standard 19-in. See Reference Perforated Cabinet.