This is an important question. If the bracelet doesn't fit correctly, a large percentage of the power will be lost leaving you with a bracelet that is not effective. Your new magnetic bracelet should fit snugly, but not tightly. If the bracelet is too loose, you will lose some of the power of the magnets. If the bracelet is too tight, it could cause your arm or hand to swell. To ensure you get the right fit, first measure your wrist with a tape measure. Wrap it leaving the tape measure flat and tight around your wrist. Then, add 1/2 inch to the measurement. This should allow for a snug fit, but also give you room for a bit of a gap giving your wrist some "breathing room".