Wrist fit simulator.

1. Place your arm flat on a table with your palm facing down — as if you were looking at a watch on your wrist.
2. Using a ruler, measure the flat distance straight across the top of your wrist, from one side to the other.
3. Important: This is not your wrist circumference. We need the flat top width — typically 45–70mm for most adults.

The flat-top width determines how much of the wrist surface the watch lugs span. A lug-to-lug measurement that exceeds your wrist width means the lugs will overhang — generally undesirable.