as pp said, if you order from
shopDisney order larges if you are an adult.
order mediums for young children.
the measurements are so horrible, but its mainly how small the ear straps are
We didn't want to go through the hassle of returning ours--we ordered 2 sets of 4. One with different mickey/minnie designs and the other set was Marvel.
I wasn't even sure if we were able to return them but once i got on the phone and heard the wait time was 87 minutes i didn't think it was worth it.
Basically, what we have done is wet them and had them stretch out over night and it seemed to have loosened the ear straps a bit.
i know a lot of other people have rigged the straps with strings to make it bearable.
be careful of stretching them out...we tore the stitching in one of the marvel masks.