Of all the ways a new strap can go wrong, the wrong size is the most common — and the most avoidable. A strap even a millimetre too wide has to be forced between the lugs; one too narrow rattles and leaves unsightly gaps. Get the size right and everything else — material, colour, style — is just enjoyable choice.
Fortunately, the measurement that matters comes down to a single number. This guide explains what that number is, how to find it for your watch in about a minute, one important exception that catches people out, and a reference table of common sizes for the watches we most often fit. If you already know your size, you can jump straight to shopping by brand from our homepage collections.
The One Measurement That Matters: Lug Width
Lug width is the distance, in millimetres, between the two lugs — the horns of the case where the strap attaches. It’s measured at the gap the strap has to fill, not the width of the lugs themselves. This is the single figure that determines whether a strap will fit your watch, and it’s the number every strap is sold by.
Most watches fall between 18mm and 24mm, and even numbers dominate: 20mm and 22mm together cover an enormous share of watches. But odd sizes exist — 19mm and 21mm are more common than people expect, particularly on certain Rolex, Omega and Tag Heuer models — which is exactly why you should never assume.
How to Measure Your Lug Width
You don’t need special tools. A ruler with a millimetre scale, or better still a cheap digital caliper, is enough.
Turn the watch over, remove or ignore the current strap, and measure the internal distance between the two lugs — the space the strap sits in. Read it in millimetres and round to the nearest whole number; you’ll almost always land on an even figure, occasionally an odd one. That number is your lug width.
If you’d like this walked through step by step with pictures, our dedicated guide on how to measure your watch strap covers it in full, including how to handle tapered straps and where people commonly go wrong.
Before You Buy: Standard Lugs vs. Integrated Fitments
Here’s the exception that trips up a lot of buyers, and it’s important enough to check before you do anything else.
Not every watch takes a straightforward straight-cut strap of a given width. Two other fitment types exist:
Integrated / proprietary fitments. Some watches are designed so the strap or bracelet flows seamlessly into the case, with a specially shaped end that only fits that model. The Patek Philippe Nautilus and Aquanaut, the Audemars Piguet Royal Oak, the Bell & Ross BR 05, and most Hublot models work this way. On these, “lug width” in the usual sense doesn’t apply — you need a strap made specifically for that watch, not a generic size.
Curved-end (fitted) straps. Many dive and sports watches, such as the Rolex Submariner or Omega Seamaster, have a case where a straight strap leaves a visible gap at the join. These take a curved-end strap that hugs the case profile. It’s still sized by lug width, but the end shape has to match the case, not just the width.
So the rule is: measure your lug width, but also look at how the strap needs to meet the case. Where fitment is model-specific, buy a strap built for your exact watch. Our brand collections are organised so the straps shown for each model are already the correct fitment.
Common Lug Widths by Brand and Model
The tables below list commonly cited lug widths for popular references across the brands we fit. Treat them as a strong starting point, not gospel: manufacturers use different case sizes across a single model line and change specifications over the years, so always confirm by measuring your own watch before ordering.
Rolex
| Model | Common lug width |
|---|---|
| Submariner / Sea-Dweller | 20mm (curved end) |
| GMT-Master II | 20mm |
| Daytona | 20mm |
| Datejust 36 | 20mm |
| Datejust 41 | 21mm |
| Oyster Perpetual 41 | 21mm |
| Explorer 40 | 20mm |
Note: Rolex sports models take curved-end straps, and Oysterflex-style rubber is model-specific.
Omega
| Model | Common lug width |
|---|---|
| Speedmaster Professional (Moonwatch) | 20mm |
| Seamaster Diver 300M | 20mm |
| Aqua Terra (38mm / 41mm) | 20mm (some 19mm) |
| Planet Ocean 42mm | 20mm |
| Planet Ocean 45.5mm | 22mm |
Breitling
| Model | Common lug width |
|---|---|
| Navitimer (41mm) | 22mm |
| Navitimer (46mm) | 24mm |
| Chronomat | 20–22mm |
| Superocean | 22–24mm |
| Avenger | 22–24mm |
Panerai
| Model | Common lug width |
|---|---|
| Luminor 44mm | 24mm |
| Luminor 40mm | 22mm |
| Luminor Due 38mm | 20mm |
| Radiomir 45mm | 24mm |
IWC
| Model | Common lug width |
|---|---|
| Big Pilot 46mm | 22mm |
| Pilot’s Watch Mark (40mm) | 20mm |
| Portugieser | 20–22mm |
| Aquatimer 42mm | 22mm (quick-change on many refs) |
Tag Heuer
| Model | Common lug width |
|---|---|
| Carrera (41–43mm) | 20–22mm |
| Aquaracer Professional 300 (43mm) | 21mm |
| Monaco | 22mm |
| Formula 1 (43mm) | 20mm |
Tudor
| Model | Common lug width |
|---|---|
| Black Bay 41 | 22mm |
| Black Bay 58 | 20mm |
| Pelagos | 22mm |
| Ranger | 20mm |
Other Brands
| Model | Common lug width |
|---|---|
| Blancpain Fifty Fathoms (45mm) | 23mm |
| Blancpain Bathyscaphe 43mm | 22mm |
| Longines HydroConquest (41–43mm) | 21mm |
| Ulysse Nardin Diver 44mm | 22mm |
| Bell & Ross BR 03 | 24mm |
Patek Philippe Nautilus/Aquanaut, Audemars Piguet Royal Oak, Bell & Ross BR 05 and most Hublot models use integrated fitments — buy a strap made for the specific model rather than by width alone.
The Other Sizes Worth Knowing
Lug width decides whether a strap fits, but two more measurements decide whether it fits you.
Strap length. Straps are made in standard, long, and sometimes short lengths, and the right one depends on your wrist size. Most straps comfortably suit average wrists, but if you have a particularly slim or large wrist, check the total length and the number of adjustment holes before buying.
Taper and thickness. Many straps taper from the lug width down to a narrower buckle width — a 22mm strap might taper to 20mm at the buckle, for instance. This is normal and affects the look. Thickness affects how the watch wears: a chunky sports watch carries a thick strap well, while a slim dress watch suits something more restrained.
Get the Size Right, Then Enjoy the Choice
Sizing a strap sounds fiddly but comes down to a simple routine. Measure your lug width, check whether your watch needs a curved end or a model-specific integrated strap, and consider length and taper for the right fit and look. Do that and you can shop with complete confidence.
The easiest way to guarantee a correct fit is to shop by your watch. Our collections group straps by brand and model so the fitment is already handled for you — browse our rubber, leather, canvas, and stainless steel collections, or start from your watch brand and find the perfect size first time.