[Sticky] What is Lug Width?
The width of a watch strap corresponds to the inner opening of the watch "lugs," known as the lug width.
A standard watch band has a straight end that will fit directly in between the watch lugs. The lug width is simply the internal width measured between the lugs (where the watch strap fits) of the watch. The lugs are located on both ends of the watch case at the 12:00 and the 6:00 positions.
You can find your watch strap size easily on the manufacturer's or watch retailer's website or you can check back of your strap. Likewise, you can measure the lug width easily using a caliper or a household ruler, which usually has a millimeter scale.
Please see attached picture to see rugs and how to measure it.