Footwear and apparel use standard US sizing. Choose your usual size on the product page. If you are between sizes, the product description will note whether a style runs large or small.
Kids shoes are listed as Baby & Toddler, Little Kids and Big Kids. Measure the foot in millimeters and compare to the size chart on the product when available.
Need a second opinion? Email reebok@gmail.com with the product name and we will help.