You can find the respective dimensions of the straps on the product page of the individual interchangeable straps.
The interchangeable straps have a short and a long side, which are attached to the top and bottom of the watch case.
If you measure your wrist circumference, please calculate the watch case with 38 mm / 40 mm / 42 mm / 34 mm / 33mm / 32mm and an overhang of the strap at the buckle.
If you are not sure which strap fits you, please let us know your desired watch model and wrist circumference. We will be happy to let you know which interchangeable straps will fit you and if you need a special length.