Not sure what size bangle is right for you?
The quickest and most accurate method is to take an existing bangle, one without a hinged mechanism and use a ruler to measure the internal diameter. Then select the same size for your new purchase.
Alternative, with a rule, measure across your palm, measuring from the outside edge of your forefinger to the outside edge of your little finger. This will be a comfortable internal diameter for your new bangle. There is a degree of flexibility. For example; If you measure 60mm across your palm, then a bangle between 55mm-65mm would fit comfortably over your hand and remain in place without risk of falling off. Do not include your thumb in the measure. When you fit your bangle over your hand, the thumb is tucked into your palm.