When shopping for kids' clothes online or by catalog, it's best to know your child's measurements. Usually, stores have a sizing chart that is based on a child's weight, height, waist and inseam. The first three are self explanatory, but not everyone knows how to measure an inseam.
If your kid is too active to keep still long enough to take a measurement, you can measure the inside seam of a pair of pants that fit him well. Place the pants on a level surface and measure the inside seam from the crotch to the hem.

