Watch Strap Taper Explained

Watch strap taper is the difference between how wide a strap is where it meets the watch (the lug width) and how wide it is at the buckle. A strap that is 20mm at the lugs and 16mm at the buckle has a 4mm taper. Our standard straps taper by 2–4mm, and that small number changes how the watch looks and how the buckle end sits under your wrist.

Below we explain how strap sizes are written, which tapers we make as standard, and how to pick one for your watch. If you only need your lug width, start with our guide on how to find your watch's lug width.

Lug width, buckle width and taper

Every strap has two widths. The lug width is measured at the end that fits between your watch's lugs, and it has to match the watch: too narrow leaves gaps beside the spring bar, too wide will not fit. The buckle width is measured at the other end, where the buckle sits.

Taper is lug width minus buckle width. Sizes are usually written as a pair, so 20-16 means 20mm at the lugs and 16mm at the buckle. The narrowing usually runs gradually along both pieces of the strap, so a well-cut strap reads as one smooth line.

There is a second taper people talk about less: thickness. Our Slim straps are 2.5mm thick at the lugs and 1.8mm at the tail, while our Padded straps go from 4.5mm to 2.0mm. Width and thickness together decide how much leather sits around your wrist.

Common tapers and the sizes we make

These are the standard lug and buckle pairs we sell. Half have a 4mm taper, four have 3mm and one, 20-18, has 2mm.

Odd lug widths such as 17, 19, 21 and 23mm tend to be less common on ready-made straps, but they are standard pairs for us. Through our custom strap builder, lug widths from 10 to 30mm and buckle widths from 10 to 24mm can be ordered. Because every strap is cut to order, any combination within those ranges can be made, including little or no taper.

How taper changes the look

This part is a visual effect, so treat it as a guide to taste rather than a rule. A larger taper, around 4mm, draws the strap in as it moves away from the case. Visually, the watch head looks more defined and the strap looks lighter, which is why we often suggest a clear taper for dress watches and slimmer cases.

A smaller taper, around 2mm, keeps the strap broad all the way round. To our eye it looks sturdier and carries the visual weight of a larger or thicker case, so it often suits sports, field and tool watches. On a 20mm watch, a 20-18 strap tends to read more casual than a 20-16.

Neither is correct in every case. Visually, a chunky watch with a busy dial can look top-heavy on a strap that narrows sharply, while a thin dress watch can look clumsy on one that hardly narrows at all.

How taper affects comfort

The buckle end sits on the underside of your wrist, the part that rests on a desk or keyboard. A narrower buckle end means less leather and a smaller buckle in that spot, which some wearers find more comfortable over a long working day. Others prefer the feel of a broader strap. Comfort also depends on the strap's thickness, length and your wrist shape, so taper is only one part of it.

The buckle has to match the buckle width. Every Cernir strap comes with a stainless steel pin buckle in the right width, in silver, yellow gold, rose gold or black, so you do not need to find one separately. If you plan to reuse a buckle you already own, measure its inside width before choosing your taper.

How to choose your taper

1. Measure your lug width first. It is set by your watch, so it is the one number you cannot change.
2. Decide on the look. As a visual effect, a narrower buckle end looks dressier and a straighter strap looks sportier.
3. Think about the watch's size. Visually, we find larger, thicker watches tend to look balanced with less taper and a padded leather strap, while slimmer watches pair well with more taper and a slim leather strap.
4. Check the length separately. Taper does not change length. Our watch strap sizing guide explains S, M and L, and the strap length finder works it out from your wrist circumference and your watch's lug-to-lug length.
5. Go custom if no standard pair fits. In the custom builder you can set the lug width, buckle width, thickness and length. Any pairing within those ranges can be made.

Frequently asked questions

What does 20-16 mean on a watch strap?

It means the strap is 20mm wide at the lugs and 16mm wide at the buckle, which is a 4mm taper. The first number must match your watch's lug width.

Does taper affect whether a strap fits my watch?

No. Only the lug width has to match the watch, along with a buckle of the right width. Taper changes the look and how the buckle end feels on your wrist.

Can I get a strap with less taper than your standard sizes?

Our standard pairs taper by 2–4mm. Through our custom builder, any lug width from 10 to 30mm can be paired with any buckle width from 10 to 24mm, so you can choose the taper that suits your watch.

Which taper should I choose for a 20mm watch?

We make 20-16 and 20-18 as standard. Visually, 20-16 gives a lighter, dressier line, and 20-18 a broader, sportier one. Pick the one that matches the look you want.