What's on your child's back-to-school list? If you're shopping for a child's backpack, ask the school or teacher for a list of required items. That way you'll know how much the backpack you're shopping for has to hold.
How much does your child weigh? The American Academy of Pediatrics recommends that a loaded backpack should weigh no more than 10 to 20 percent of your child's body weight; the American Chiropractic Association sets a more conservative limit of 5 to 10 percent.
What is your torso size? Packs are sized by torso length, not overall height, and knowing your torso measurement can help you get the right size. Measure from the bony bump at the base of your neck (your seventh cervical vertebrae) to the top of your hipbones.
Will it fit your hips? If you're shopping for backpacks with hip belts, knowing your hip circumference can help you choose the right size right off the shelf. Measure around your hips at the same level with the top of your hipbones and make sure to keep the measuring tape level.
What are the school's rules? Many schools have banned rolling backpacks as a tripping hazard and many wheeled backpacks won't fit in a locker. Check with your child's school to be sure they allow wheeled backpacks and (if possible) measure the locker before buying.