Free online rack space calculator to determine server rack U space requirements, equipment placement, and rack utilization. Number of DevicesTotal quantity of equipment (servers, switches, etc. Height per. A server rack space calculator is an essential IT utility designed for data center managers, system administrators, and network engineers to meticulously plan the physical layout of their equipment cabinets. This calculator helps you plan rack layouts by calculating the total rack units. Convert rack units to inches, feet, and centimeters, then add devices with different U heights and quantities to calculate total rack space, rack count, and utilization for common rack sizes. Specify the height of each device in Rack Units (e.