Of all the measurements that go into a watch strap, lug width is the one that cannot be approximately right. A strap that is a little long can be worn on a different hole. A strap that is a millimetre too narrow at the lugs shows a gap on both sides of the case for as long as you wear it.
The good news is that it takes a minute to measure. This guide explains what lug width is, how to measure it on your watch or on a strap you already own, and when a measurement alone is not enough.
What lug width means
The lugs are the two pairs of horns that extend from the top and bottom of the watch case. The strap is held between them. Lug width is the inside distance between the two lugs of one pair, in millimetres. It is also the width of the strap where it meets the case.
Lug width is not the same as case diameter. Two watches with the same case size can have different lug widths, and a large case does not always mean a wide strap. Many dress watches use narrow lugs for a finer look on the wrist, and some sports watches use wide ones.
The other end of the strap, where it meets the buckle, is usually narrower. That is the buckle width, a separate measurement covered in the watch strap sizing guide.
How to measure lug width
On the watch
- Lay the watch face up on a soft cloth.
- Use a ruler or calliper with millimetre markings. A calliper is easier to read, but a good ruler works.
- Measure the inside distance between the two lugs at the top of the case, from the inner face of one lug to the inner face of the other.
- Repeat at the bottom of the case. The two figures should match.
On a strap you already own
If you have a strap that fits your watch well, measure the strap itself at the very end that meets the case, across its full width. This is often easier than measuring between the lugs, and it gives the same number.
In the watch’s documentation
Many manufacturers state the lug width or strap width in the specifications for a reference. If your figure and the documentation agree, you can order with confidence.
Why one millimetre matters
Most lug widths are whole millimetres, and the common sizes sit close together: 18, 19, 20, 21, 22 mm. The difference between neighbouring sizes is small to the eye and large on the wrist.
- A strap that is too narrow leaves a visible gap between the leather and each lug. The watch looks loose, and the strap can shift sideways on the spring bar.
- A strap that is too wide has to be squeezed between the lugs. The edges buckle or wear quickly, and the strap does not sit flat.
When I cut a strap, the lug end is cut to your exact width. That is why the lug width you choose in the configurator matters more than any other option. Depending on the watch, the configurator offers widths from 12 mm up to 25 mm; for watches with a fixed geometry, such as the Santos 100 (20 mm on the M case, 23 mm on the XL), the right width is already set by the model you choose.
If your measurement falls between two sizes, do not round it yourself. Measure again with a calliper, or send me the reference of your watch and I will confirm the width.
Straight ends and special strap ends
Most watches use straight strap ends: a spring bar runs through the end of the strap and clips into small holes in the lugs. For these, lug width is the main measurement, together with the type of spring bar. The configurator for watches like the Cartier Tank lets you choose a straight spring bar or a straight quick-release spring bar.
Some watches do not work this way at all:
- QuickSwitch and other integrated systems, such as the current Cartier Santos, where the strap end has to be made for the system.
- Custom end pieces, such as the Santos-Dumont, where a spring bar works inside its own end piece, or the Audemars Piguet Code 11.59, where the strap integrates closely with the case.
- Curved or shaped ends that follow the profile of the case.
For these watches, the width alone does not describe the fit. The shape of the strap end and the way it attaches matter just as much.
When to send a photo of your watch
Please send me a photo, or at least the reference number, before ordering if:
- your watch has integrated, curved or shaped strap ends;
- your measurement falls between two sizes;
- the top and bottom lugs give different figures;
- you cannot find your watch in Shop by Watch.
A clear photo of the case from the side and from the back, with the strap removed if possible, tells me more than a measurement. You can attach it to a message through the contact page.
Quick reference
| Question | Answer |
|---|---|
| What is lug width? | The inside distance between the lugs, in millimetres. Also the strap width at the case. |
| How do I measure it? | Calliper or ruler between the inner faces of the lugs, or across the end of a strap that fits. |
| Is it the same as buckle width? | No. The buckle end is usually narrower. |
| What if my figure is between sizes? | Measure again, or send me your reference before ordering. |
| Does it apply to integrated straps? | Only partly. Integrated and custom ends need the model, and often a photo. |
