Science, Tech, Math › Social Sciences Sizing Guide for Children's Backpacks Share Flipboard Email Print Chris Adams/Thoughtco.com Social Sciences Ergonomics Psychology Sociology Archaeology Economics Maritime By Chris Adams Engineering Expert B.I.D, Industrial and Product Design, Auburn University Chris Adams is a human factors engineer who writes about ergonomics and has 11 years of experience in the field. our editorial process Chris Adams Updated November 18, 2019 A good ergonomic backpack should be no larger than a child's back. To simplify matters, take two measurements of your child's back and use them for the maximum height and width of the backpack. This will ensure that the backpack is the proper size for the child's body. Find the Height Find the maximum height by measuring the distance from the shoulder line to the waistline and adding two inches. The shoulder line is where the backpack straps will actually rest on the body. This is located about halfway between the neck and the shoulder joint. The waistline is at the belly button. The backpack should fit two inches below the shoulders and up to four inches below the waist, so adding two inches to the measurement will produce the right number. Find the Width The width of the back can be measured at a number of locations, each with different results. For a backpack, the core and hip muscles usually carry the most weight. This is why the backpack should be kept centered between the shoulder blades. To find the proper width for a backpack, measure between the ridges of your child's shoulder blades. Adding an extra inch or two here is acceptable. Size Chart for Children's Backpacks Chris Adams If you cannot measure your child for some reason—they refuse to sit still, or you cannot find any measuring tools—you'll have to make an educated guess. This chart will help ensure that that guess is as accurate as possible. The chart shows the maximum heights and widths for the average child of a certain age. Make adjustments as necessary. Remember that it is always best to be on the conservative side—better that your child ends up with a backpack that is slightly too small than one that stresses their shoulders because it is too large. Also, don't forget to adjust the shoulder straps so that they fit comfortably on your child's body. If the straps are too loose, the bag will hang down below their waist, causing undue stress. If the straps are too tight, however, they may pinch your child's shoulders and limit the range of movement. Double-check this at the start of each school year to make sure the bag still fits. Other Considerations Size is not the only thing to consider when selecting a backpack for your child. You'll want to pay close attention to other details, too, including the bag's material. If your child is active, they may prefer a bag made out of lightweight, breathable material such as nylon rather than something heavier such as faux leather. If your child is often outdoors, or if you live in a rainy climate, consider a water-resistant bag made out of something such as waxed cotton. Another thing to consider is how much storage the bag offers. Some bags are fairly simple, with room for a three-ring binder and some books, while others are packed with compartments for laptops, phones, tablets, and other devices. Find out what items your child is required to bring to school and make sure the backpack can accommodate them.