Havaianas are a brand of flip-flops available in more than 60 countries. The sandals feature a distinctive textured rice pattern on the sole, and come in a wide variety of colors and styles. The sandals originated in Brazil, and are often sold in European sizes, which requires a quick conversion from U.S. shoe sizing.

Start with your regular U.S. foot size, or have your feet measured at a shoe store.

Find your U.S. foot size, if you aren't sure of it. Place your foot on a piece of paper and trace around it with a pencil. Measure the distance between the two longest points using a ruler. Reduce the number by 1/5 inches. This is the number of inches you will use to determine your shoe size.

Use a detailed shoe sizing chart to determine your U.S. shoe size. If your measurement is 9 1/16 inches, for example, you will find on the chart that your shoe size is a U.S. size 7.

Convert your U.S. size to a European size. Havaianas are often sold in European sizes. A U.S. size 7, for example, is a European size 38. European sizes are not usually available in half sizes. Use the larger size if you normally wear a half size in the U.S.