There is also a table for several watches that are commonly use to change their strap :
You can also follow below table to do fitment which size of strap that you have to choose. Do wrist measurement as the picture below to get exact size of your wrist :
Center hole mean the very ideal strap hole position that fit your strap in your wrist. This is the length of the ideal hole position from the lug (the top of the strap). The most ideal strap size is when the buckle/clasp right in the center of the bottom of your wrist. After we know your wrist size, we will choose the most suitable strap size and follow the center hole guidance above, all we need to do after that is adding hole up and down to get more flexibility for you to use.