Lug width is the distance between the inside faces of the two lugs on a watch case. It is given in millimetres. When you change a strap, it matters more than any other measurement of the watch, because the new strap has to fit the gap between the lugs.
What are lugs?
Lugs are the metal parts sticking out from each end of a watch case. They are also called horns. They are the points where the strap, band or bracelet is fixed to the case, and they hold it in place. A spring bar spans the gap between each pair of lugs and holds the strap. On some straps the bar passes through the strap itself. On others, the band is fitted between the lugs. Either way, the width of that gap decides which straps will fit.
How do you measure lug width?
Measure across the inside of the lugs with calipers or a millimetre ruler. Take the reading from the inner edges of the lugs, not from their outer edges. The figure you want is the space between the lugs, not the width of the case at that point. Note the result in millimetres, the same unit used for case size. Straps are made only in whole-millimetre widths, so a careful reading makes it easier to pick the right one.
What lug widths are common?
On men’s watches, lug width is most often somewhere from 18 mm to 22 mm. Straps are usually made from 16 mm to 24 mm wide, and always in whole millimetres. That range covers the common men’s sizes, with some room on either side. Before you buy a new strap, check your watch’s lug width first. It tells you which strap width to look for, and it matters more than any other measurement when you make the change.
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