Whether you’re looking for high-performance athletic footwear or casual, everyday kicks, it’s important to wear well-fitting shoes that comfortably support your feet. Shoes that don’t fit properly can leave your feet feeling uncomfortable, achey or blistered. And unfortunately, wearing the wrong size shoe is more common than you might think.

A 2018 study from the Journal of Foot and Ankle Research found that up to two-thirds of people may be wearing shoes that fit improperly, and that wearing the wrong size is associated with foot pain and poorer foot health overall.

So, how do you know if you’re wearing the right shoe size? Finding the correct shoe size starts with accurately measuring your feet. Read on to learn how to measure your foot size and how to find your shoe size in Nike footwear. Plus, check out additional tips for picking out comfortable, supportive shoes that meet your needs.

(Related: 8 Ideas for Storing Shoes)