Chelsea rain boot with deep elastic goring on sides .To measure your foot length, sit down on a chair and place foot flat on a piece of paper. Trace the foot by holding a pencil vertically and outlining the foot. The longest toe and back of heel are the most important measurements. Using a ruler, measure the distance from the bottom of the heel to the tip of the longest toe. Record the result in both inches and centimeters and use these measurements to find your size in the chart. If one foot is larger than the other, the measurements for the larger foot should be used.