To measure your feet, first measure from the heel to the tip of your longest toe. Then, use the conversion tables to find the closest measurement in inches. Next, measure the widest part of your foot and match it to the width chart.
For accurate results, flatten your foot and shift your weight forward, and try measuring later in the day when your feet are naturally expanded. If you're between two sizes, choose the larger one. Keep in mind, athletic shoes usually run half a size larger than dress or casual shoes—so if you're a size 10 in athletic shoes, you'll likely be a 9.5 in dress or casual shoes.