To measure your foot, place a blank piece of paper larger than your foot on the floor against the wall.
Tape the paper down to the floor. Stand on the paper with your heel slightly touching the wall.
Then use a pen to draw a straight line touching the outermost point of your toe.
Use your ruler or measuring tape to measure the length from the bottom of the paper to the top line that you drew.
This number is your actual foot measurement, you can convert them to the appropriate size using the shoe size table.
* Because the foot is three-dimensional, any two-dimensional measuring tool, such as the method above, can only approximate your true shoe size.