How to Choose the Right Leather Watch Strap Size

October 4, 2026

Teal alligator leather watch strap on the wrist with a gold dress watch

A leather watch strap can change the whole personality of a watch — but only if it fits. Before you choose a colour or a leather, you need two numbers: your watch's lug width and the strap length that suits your wrist. This guide walks you through both in a few minutes, with nothing more than a ruler and a tape measure.

1. Measure your lug width

Close-up of an alligator leather watch strap end showing strap width at the lugs — The strap width at the lug end should match the gap between your watch lugs.

The lugs are the two "horns" on each side of the watch case where the strap attaches. Lug width is the distance between the inner edges of those lugs, measured in millimetres. It's the single most important measurement, because the strap has to sit snugly between the lugs with no gaps and no squeezing.

Use a ruler or caliper and measure the inside gap between the lugs, not the outside of the case.
Check the caseback or manual. Many watches list the lug width (for example "20mm") in the specifications.
Measure the old strap where it meets the case if the watch isn't handy.

Most men's watches use 18mm, 20mm, 22mm or 24mm lugs; many women's and vintage watches use 12mm to 18mm. If your measurement lands between two sizes, double-check — a strap that is even 1mm too narrow will shift and look loose.

2. Choose the right strap length

A two-piece leather strap has a long side (with the holes) and a short side (with the buckle). Together they determine whether the strap closes comfortably on your wrist.

Wrap a soft tape measure (or a strip of paper) around your wrist where you wear your watch.
Note the circumference in centimetres or inches.
Compare it with the length listed on the strap. The middle holes should line up with your wrist size so you have room to adjust.

As a rough guide, standard straps comfortably fit wrists of about 15–19cm (6–7.5in). If your wrist is noticeably smaller or larger, contact us before ordering and we'll advise on the best length.

3. Buckle or butterfly clasp?

Black and yellow Epsom leather racing watch strap worn on the wrist — A well-fitted strap sits flat and leaves room for one finger underneath.

A standard pin buckle is classic, light and easy to adjust. A butterfly (deployant) clasp folds closed under the wrist, so the leather isn't bent through a buckle every day — a good choice for exotic leathers and for anyone who takes their watch on and off often. Our watch straps let you choose either option on the product page.

4. Straight or curved ends?

Most straps have straight ends, which fit the majority of watches. Some cases are designed for curved-end straps that follow the shape of the case and close the gap between strap and watch for a seamless look. If your current strap has a curved end, choose "Curved End: Yes".