The average men's US ring size is 10. For women it's a 6.
Men's bracelets are 8 or 8.5 inches. Women's bracelets are 7 or 7.5 inches.
1. Measure your wrist just below the wrist bone, where one would normally wear a bracelet, with a flexible measuring tape, string, or a strip of paper.
2. If you are using string or a plain strip of paper, then measure that paper strip with a ruler to determine your wrist size.
3. Add 1/2 inch to your wrist size for a comfortable fit.