How To Measure Your Wrist Size. Open your hand (doing so will ensure you get the real size of your wrist when it’s the largest) snuggly wrap a measuring tape around your wrist. Bring the ends of the tape closer and read the difference between the numbers on the tape.
If you are using a plain strip of paper, then measure that paper strip with a ruler to determine your wrist size. Tape the edges of the paper together to form a circle around your waist, then measure the number of papers you used by either 8.5 inches (22 cm) if you used the short side or 11 inches (28. 39mm, 40mm, and 42mm range will fit best.
Just like it is important to wear clothes that sit well, it is equally important to wear bracelets that sit properly as well.
Once you've done that, measure how long the piece of string is. Take a scale and measure the length; Place the tape around your wrist in the same area you wear a watch to determine the circumference of your wrist in inches. To get your wrist measurement if you’re using a strip of paper or string, simply lay it flat on a surface and measure the length from your starting point to the end mark you’ve made, and then add to that measurement your desired inch allowance.