How To Measure Your Wrist For A Watch. Between 6 and 7 inches (15 to 17 cm), pick a 38 to 42 millimeter diameter. Hold your watch face on its side and measure from one spring pinhole to the other.
Bring all your fingers together, specifically being sure to bring your thumb in so that it is touching your pinkie finger. Mark where the two ends meet then lay the thread out flat on a ruler and measure the distance. Find your watch head size by using a ruler or check the manufacturer for information.
It should fit comfortably but not loose.
Measure up past your wrist bone if you like your watch to have a snug fit. Put the end of the tape right in the middle of your wrist. Cut out the length chart below along the dotted lines. Don't pull it too tight.