Since the x-kilt has a narrow apron, the pleats come around on the sides. My X-kilt has 12 pleats, but I widened the apron to 12". My other box pleat made on the X-kilt model but with a standard 21" apron has only 9 x 3.5" pleats. An easy check - 14x3 = 41+11 = 53. Is that your rump measurement?

Brian

Hope this helps