How to Measure Your Watch's Lug Width
Your strap size is the lug width — the gap between the lugs, in millimetres. Here's how to measure it in under a minute, no tools required.
Step 1 — Calibrate
Hold any bank/credit card flat against the screen and drag the slider until the dashed box matches the card's width exactly.
BANK CARD — 85.6 mm
Step 2 — Measure
Drag the two gold markers to the inside edges of your watch's lugs. The reading is your lug width.
20.0 mmnearest standard size: 20 mm
Lug width vs lug-to-lug
Lug width is the strap width you buy. Lug-to-lug is the tip-to-tip length of the case, which decides how big the watch wears — it doesn't affect strap size.
Common strap sizes
Dress watches are typically 18–20mm, divers and sports watches 20–22mm. Odd sizes (19mm, 21mm) exist and are worth double-checking before you buy.
Lug width FAQ
What is lug width?
Lug width is the distance between the two lugs where the strap attaches, measured in millimetres. It's the number you use to buy a strap (e.g. 20mm).
How do I measure lug width without a caliper?
Use a millimetre ruler across the gap between the lugs, or use the on-screen ruler on this page after calibrating it with a bank card.
Are watch strap sizes always even numbers?
Usually — 18, 20 and 22mm are most common. Some watches use odd sizes like 19mm or 21mm, which are harder to shop for.