See my response to one of your other shotgunned questions about mudroom dimensions in the Fine Homebuilding article(s) on the subject. Even w/o a definitive answer, you can get pretty close to the dims using hints provided by the objects shown. This looks like a custom piece that technically wasn't built in (note the gap @ ceiling above the unit). I think you just adapt your sizing to the space you're considering, round up or down the number of cubbies as appropriate, etc.