How to Measure Your Watch Strap Size: Lug Width and Length
To measure your watch strap size, take two numbers: the lug width, which is the inside gap between the lugs in millimeters, and the strap length, written long side / short side. Measure the lugs with a ruler, then copy a strap you like or measure your wrist. For example, a 7-inch wrist takes 125/75 mm.
What two numbers make up a strap size?
A strap size is always a width and a length. The width has to be exact, because the watch sets it. The length has to be comfortable, because your wrist sets it. Get both right and everything else is a matter of taste.
- Lug width: the gap between the two lugs, in millimeters. XILUGS cuts 12 to 24 mm.
- Buckle width: the narrower tail end where the buckle sits, usually 2 mm less than the lug width.
- Length: written long side / short side, for example 115/75 mm.
- Thickness and profile: Flat, Padded Domed, Padded Square or Padded Full, picked by name on the builder.
Stitch color, edge color and buckle finish change nothing about fit. The four measurements above decide whether the strap goes on the watch and closes on your wrist. Our watch strap size guide holds the full reference tables; the sections below explain how to arrive at each number yourself.
How do you measure lug width?
Lay the watch face-down on a table and measure the inside distance between the two lugs, the horns the spring bar passes through. A steel ruler with millimeter marks is enough; a caliper is better if you own one. Read the gap itself, not the outside of the case, which is always wider.
This figure must be exact. A strap 1 mm too wide will not fit between the lugs, and 1 mm too narrow leaves a visible gap at each side of the case. Write down what you measure, even if it is an odd number.
- No ruler? Many straps have the width printed on the underside near the lug end.
- The watch brand's specification for your reference usually lists the lug width too.
- If two sources disagree, trust the measurement taken on the watch.
Every XILUGS strap is cut by hand against a steel rule rather than stamped from stock sizes, so an odd width costs no more than an even one. Tell us 19 mm and the strap is cut at 19 mm.
Do odd lug widths like 19 or 21 mm need a special order?
No. Odd widths are normal on many dress and vintage watches, and they are the sizes stock straps most often skip. Order the number you measured, and do not round it to the nearest even size: a 19 mm watch on a 20 mm strap will not close cleanly between the lugs.
If you own one of the watches we get asked about most, our model guides go deeper on fit and leather choice:
- Grand Seiko strap guide for 19 mm lugs
- Omega Speedmaster leather strap picks
- Tudor Black Bay 58 strap fit guide
- Hamilton Khaki Field 20 mm and 22 mm fit guide
- Seiko Presage and 5 Sports strap sizes
Each one confirms the lug width for that model and then focuses on profile, thickness and color, so you can skip straight to the leather once you have measured.
How do you measure watch strap length?
A strap comes in two pieces. The long side carries the holes; the short side carries the buckle. Length is written long/short, so 115/75 mm means a 115 mm holed side and a 75 mm buckle side, each measured from where it leaves the lug to its tip.
The quickest method is to copy a strap you already like. Lay it flat, measure each half, and write both figures down. With nothing to copy, wrap a soft tape just above the wrist bone, snug but not tight, and read the circumference.
Then find that circumference in the table below. Each wrist range maps to one long/short length. If you would rather not do the arithmetic, send us the wrist figure with your order and we will choose the length.
What strap length fits a 7-inch wrist?
A 7-inch wrist is about 17.8 cm around, which falls in the 17.6 to 18.5 cm band of our size guide, so it takes a 125/75 mm strap. The middle of the chart looks like this:
| Wrist (cm) | Wrist (in) | Strap (mm) |
|---|---|---|
| 15.6–16.5 | 6.1–6.5 | 115/70 |
| 16.6–17.5 | 6.5–6.9 | 115/75 |
| 17.6–18.5 | 6.9–7.3 | 125/75 |
| 18.6–19.5 | 7.3–7.7 | 125/85 |
| 19.6–20.5 | 7.7–8.1 | 135/85 |
Smaller and larger wrists are covered too, from 105/65 mm for wrists up to 14.5 cm to 135/105 mm for 21.6 to 22.5 cm. If you sit at the edge of a band or are moving to a padded strap, take the next size up. Because nothing is cut until you order, you can also give us your own two lengths.
Does buckle width matter as much as lug width?
It matters, and it is the figure people forget. A strap usually tapers from the lug end to the buckle end, so a 20 mm strap often finishes at 18 mm. If you plan to reuse a buckle from an old strap, measure its inside width and tell us that number, or the buckle will sit loose or not slide on at all.
Straight straps with little or no taper are possible too, such as 20 mm at both ends, and they look more modern on a tool watch. Because both ends are cut by hand, you choose the taper. The keepers are sized to the finished strap at step 13; our guide to what the two keeper loops do explains the options.
How do thickness and profile change the fit?
A flat strap slips under a shirt cuff and softens quickly, which suits a thin dress watch. A padded strap lifts a heavy case and keeps its shape, which suits a diver or a large chronograph. Padding also takes up a little wrist room, so size up when moving from flat to padded.
On the XILUGS builder, Padded Domed has a gentle dome down the middle, while Padded Square and Padded Full fill more of the lugs on large cases. On round cases, a curved end (+$15) closes the small gap a straight end leaves. Our article on which profile suits your case height covers this step by step.
Where to order once you have your numbers
Every strap below is cut to the measurements you give us, in any lug width from 12 to 24 mm:
- Design Your Own Watch Strap, from $69: set width, length, thickness and profile in a live preview.
- Flat Taupe Togo calfskin strap, from $69: a soft pebbled everyday option.
- Flat Brown Waxed Cowhide strap, from $69: pull-up leather that changes with wear.
- Sky Blue Epsom leather strap, firm and shape-holding, from $75.
Not sure which numbers to enter? Order a bespoke custom strap and send us your measurements to check first, or browse regular leather watch straps by material.
FAQ
What strap length do I need for a 7-inch wrist?
A 7-inch wrist is about 17.8 cm around. On the XILUGS size guide that falls in the 17.6 to 18.5 cm band, which takes a 125/75 mm strap. For a looser fit or a padded strap, consider the next size, 125/85 mm.
Can you make a strap longer than 135/105 mm?
The chart stops at 135/105 mm for wrists up to 22.5 cm. For a larger wrist, choose the custom size option, give us your wrist measurement, and we will confirm the lengths before cutting.
How do I measure if I have no millimeter ruler?
Measure an existing strap against anything marked in millimeters, or send us a photo of the watch next to a coin for scale. We would rather check than have you guess.
Does a butterfly clasp change the length I need?
Yes. A butterfly clasp closes differently from a pin buckle, so mention it with your wrist size and we will adjust the two lengths. The clasp adds $10 to the strap price.
What if the length turns out wrong?
Straps cut to a custom spec are final sale unless faulty, which is why we ask you to measure twice. Email your numbers before ordering and we will check them for free.
Once you have both numbers, check them against the size guide chart one last time before you order.
