Shoes sizes are more complicated than just numbers and halves. In shoe sizes, letters represent the width of a shoe. It is important to wear the shoe right width. Otherwise, you can end up wearing a shoe either too large or too small in length while trying to compensate for the width. Shoe stores have special devices for measuring feet. At home, you can just use a pen or pencil and paper.
Lay a sheet of paper on a hard floor.
Place your foot on the paper, and put your weight on it.
Outline the shape of your foot with a pen or pencil.
Draw a vertical line at the widest point on each side of the foot. The lines should be perfectly parallel.
Draw a pair of parallel horizontal lines at the top of the tallest toe outline and at the bottom of the heel.
Measure the length and width between the two sets of lines.
Determine your numerical shoe size from a shoe size chart appropriate to your gender.
Determine your width from a chart.
If you are between sizes, choose the larger size. Men's sizes are two sizes larger than women's---for example, a men's size 10 is a women's size 12. The width of women's normal-width shoes is typically a B, and men's normal-width shoes are generally a D, wider than women's shoes.
Do not to tilt your pen or pencil when you draw your foot outline. Keep it perpendicular to your paper.