Wide Width, Karolyn One-Band Slip-On Flat Sandal - Steve Madden

Remove shoes and socks, stand on a sheet of paper with feet comfortably aligned to each other at approximately shoulder width apart, and have your body weight evenly distributed between your feet.
Using a pencil, gently trace the outline of the foot onto the paper, ensure the pencil is kept vertical. The trace will be more accurately done by someone else.
Draw a straight line at the longest toe and at the heel, these two lines must be parallel of each other.
Draw a vertical line connecting these two parallel lines. This right angle (90 degree) is your foot length.
The foot width is measured by a straight line connecting the widest spot of your foot.
If your measurements fall between two sizes, move up to the larger size for a better fit.