A server information handling system rack has an adjustable depth to fit different sized server rack sleds and adapt the rack to different sized data centers. Fixed vertical supports couple to fixed horizontal supports to define a rack interior that adjusts in depth by sliding horizontal supports that change a position of extensible vertical supports coupled to the sliding horizontal supports. When a desired rack depth is set, the fixed horizontal supports and sliding horizontal supports are affixed to each other, such as with a screw that couples to a threaded nut of the fixed horizontal support.