HOW TO MEASURE A KILT
Measure Around the 'Waist': The simple, but little known technique is to measure 1-2 inches ABOVE THE NAVEL.
Not the same size as your trousers: The kilt is meant to trim your middle and enhance your shape by cinching your midsection. Often, your waist will be larger or smaller than your trousers.
Order smaller: If you're 36.5 inches around your waist, order a 36. If you're 35.5" exactly, order a size 34. As kilts sit at your belly, your belly has a tendency towards elasticity and you're best ordering a tighter fit than a looser one.