WATCH SIZING: Below is a US to Metric Conversion and a Metric to US. Also, some basic measurements to help you determine if the watch that you are looking for is going to be the right size.
1 inch= 2.54 millimeters (mm)
1 foot= 30.48 centimeters (cm)
1 millimeter (mm)= 0.039 inches
1 centimeter (mm)= 0.039 inches
Lug Width: This will tell you how wide the band it.
Case Size: This will tell you the width of the actual watch. Both the Lug Width and Case Size won’t tell you if the watch will be too small, fit right or be too big.
The lug to lug width and the band size are the main measurements for a size determination. The lug to lug width is the space between the band (the actual watch) & the band size. Just add these 2 numbers up and measure your wrist. Also keep in mind where an adjustable band is sized for the pictures you are looking at.