Each wool mitten stretches differently but I have found these size fit most hands. These sizes are approximate as some hands are different shape. Measure from the crease in the wrist (where your watch might rest) to the end of the longest finger.
Small-Medium: 7 1/4" Medium: 7 1/2"
Medium Large: 7 3/4" Large: 8"
Extra Large: 8 1/2
WASHING INSTRUCTIONS: You can machine wash and dry but I recommend hand washing for longer wear.