Measure the circumference of your hand around the widest part of the palm not including the thumb, just below the base of the fingers. Giordana gloves are race style, if you have "fat" hands you may want to size up.
Familiarity: I returned this product before using it
Fit: True to size
Size Bought: Large
I was waffling between 2 & 3 stars but after re-reading the description of these shoe covers on the Giordana website I decided that these are as described - water-resistant not waterproof. The description is a little misleading as the covers incorporate a waterproof membrane, which seems to be true. However, the seams are not sealed and after just a couple minutes of spraying the shoe covers with a hose my feet were soaked. They also describe these as "mid-weight" and that's simply not the case. These are thin with no lining and no insulation. That being said, they do have a nice, snug fit and they have reflective accents which is nice. These would be good for Autumn or Spring riding when it's cool but not cold and the roads are relatively dry. Not recommended for winter riding when the temps drop and the rain is falling.