There are few things that strike terror in boys and young men than the idea of clothes shopping. So if he needs a new pair of jeans and he's not there to try them on, you're stuck. However, if you are looking at a pair of size 16 jeans and you know your kid's measurements, converting the size into inches will give you a good idea if the pants will fit. A conversion chart will make this simple; and once you have made the conversion, you won't have to do it again, hopefully, for a while.
Refer to an online size conversion chart for standard sizes, such as one available from SchoolUniforms.com. A size conversion chart provides dimensions in inches for the leg and waist measurements of a pair of pants. Leg, inseam and length are all used interchangeably.
Note the waist size in inches. The waist size in inches for a pair of size 16 pants is 28 inches.
Find the inseam length in inches. The inseam length in inches for a pair of size 16 boy's pants is 30 inches.
Find a brand you like and stick with it. This helps make sizing easier since you will always know how a particular size will fit.
Remember, clothing size conversions into inches are not always precise. Sizes can differ across brands.