Measured: Hoop size is quoted as the outer diameter, measured straight across the widest point of the circle, with the usable inner opening smaller by twice the tube thickness.
The basics
What to know about hoop size
Diameter changes a hoop more than material, finish or stone does. Move from 12 millimeters to 60 and the same design changes completely. It goes from something you forget you are wearing to the loudest thing on you. The weight on your lobe rises alongside.
Size is quoted as the outer diameter, measured straight across the widest part of the circle, almost always in millimeters. The opening you actually push through your ear is smaller by twice the tube thickness. A 12 millimeter hoop made from 3 millimeter tube leaves only a 6 millimeter gap. On small hoops that inner figure decides whether the earring fits a thick lobe at all.
Coins make the scale concrete. A US dime measures about 18 millimeters across and a quarter about 24. That makes a small hoop roughly dime sized and the smallest medium a little wider than a quarter. Weigh the bands against tube thickness too, because two hoops of one diameter can differ threefold in grams.
