SPOKANE, Wash.—It’s time for back to school shopping and on that checklist, could be a new backpack.

KREM 2 spoke with an expert who gave some tips on how to pick out the right backpack.

Chiropractor Dr. Chad Johnson said for starters, it is not about the backpack itself, but what is inside it.

Johnson said backpacks should never weigh more than 15 percent of a person’s bodyweight. He said this is something to keep an eye out for if children have a lot of classes with heavy textbooks.

“We are designed to be upright, and the more weight that's in that pack, the more you'll have to start changing your posture to hold that properly, and that adds that much more strain on the body and that stress and strain adds up time after time after time,” said Johnson.

Next, Johnson said parents should make sure the pack is the right fit for the child’s body.

“It shouldn’t look like it’s swallowing up all of his or her back,” said Johnson.

Thicker straps are always better, too. Even better than thick straps are packs with waist and chest straps because those disperse weight better, according to Johnson.