When it comes to comparing men's and boys' shoe sizes, there is no comparison. The standard sizing scale for men's and boys' shoes in the United States does not have any overlap; that means you won't be able to find a pair of shoes sized for boys in a comparable men's size. Also keep in mind there is no standard sizing chart for shoes; while there are some similarities, each manufacturer determines the exact measurements that constitute a shoe size.

Measure your feet using a ruler. Place your heel on the back edge of the ruler at the "zero" mark. Place the length of the ruler under your foot so it runs from your heel to your big toe. Note the length: for boys' sizes, it will likely be between 3 1/2 and 9 inches; men's sizes typically run from 9 inches and up. If your foot is longer than a standard ruler (12 inches), use a tape measure or yardstick instead.

Make sure to measure both feet. Sometimes your feet will not be the same size. If you are unable to buy shoes in two different sizes to accommodate this difference, buy a pair in the larger size. Wearing shoes that are too small can lead to bunions and other foot problems.

Take into account the width of your feet. Again, different manufacturers have different ways of measuring width; some use a small/medium/large scale, while others use letters (A to E) to indicate width.

Compare the length of your foot to the sizing chart for your preferred brand of shoes. Again, the size that goes along with a corresponding measurement varies from brand to brand. For example, a man with feet that measure 10 inches long will wear a size 7 1/2 in shoes made by the online retailer Men's Flair, but size 8 in shoes made by the SoftMoc company.

Note the sizes of boys' shoes compared to men's shoes. Shoe sizes for boys start at size 1 and continue to size 13, before beginning again at 1. Shoe sizes for boys then go up to size 4 before men's shoes start at size 5. There is a size difference between a boys' size 4 and a men's size 5; the exact difference in length will depend on the manufacturer of the shoe.