WHICH SIZE OF BRACELET IS RIGHT FOR YOU?
Using a soft fabric measuring tape or a length of string (which you can place against a ruler) measure the widest part of your wrist, adding between 2 to 5cm's, depending on how loose you want to wear the bracelet, and also how many charms you think you'll end up buying. Bear in mind that over time you may buy many more charms and so the capacity of the bracelet for more charms will be determined by your initial bracelet purchase. For a very full charm bracelet you may need to go to the full 5cm's, but for just a few charms (4 or 5) then an extra 2 to 3 cm's will be sufficient. But please remember a very loose bracelet can be just as annoying as a very tight one, so think carefully about your future charm purchases and how many you think you'll end up buying.
If you wish to purchase a bracelet as a secret gift for a friend or a loved one, you can always try measuring the inside of their watch-strap, or another bracelet.