How to Measure Your Watch's Lug Width

The single most important number when choosing a strap is your lug width — the gap between the two lugs where the strap attaches, measured in millimetres. Get it right and the strap sits flush; get it wrong and it won’t fit. Here’s how to find yours in under a minute.

What is lug width?

Lug width is the distance between the inside edges of the two lugs (the arms that hold the strap) where the strap meets the case. On most watches it’s an even number — commonly 18mm, 20mm, 21mm or 22mm.

How to measure it

• With a caliper: the most accurate — measure the inside gap between the lugs.
• With a ruler: lay the watch face-up and measure across the gap where the strap sits, rounding to the nearest millimetre.
• Check the old strap: many straps have the width printed on the back near the buckle.

Common widths for popular watches

As a guide, most Rolex GMT-Master II, Submariner (40mm), Daytona, Explorer and Omega Speedmaster/Seamaster models take 20mm. Some 41mm models and the Yacht-Master 42 take 21mm or 22mm.

Not sure? We’ll do it for you

Use our Find Your Fit tool — pick your exact watch and it shows the correct width and the straps made for it. Then browse rubber, elastic loop or Saffiano leather straps in your size. Still unsure? Message us — we reply within 15 minutes.