By JackCoHenry Singapore | Bespoke Watch Straps and Fine Leather Goods
21mm is one of the less common lug widths — often found on specific Breitling references, certain vintage pieces, and a handful of contemporary sports watches. Ready-to-wear options are limited by volume, which is precisely where bespoke becomes the practical choice rather than the indulgent one. At JackCoHenry, 21mm is one of the widths we cut regularly. This guide covers the watches that take it, the leathers that suit them, and what to look for.
Which Watches Use 21mm?
21mm appears on watches where the manufacturer opted slightly outside the standard 20mm or 22mm increments — often for ergonomic or aesthetic reasons specific to the case design.
|
Brand |
Model / Reference |
Lug Width |
Notes |
|
Breitling |
Navitimer (selected vintage refs) |
21mm |
Some pre-2009 references |
|
IWC |
Aquatimer (selected refs) |
21mm |
Certain case sizes |
|
Glycine |
Combat Sub / Airman (some) |
21mm |
Selected models |
|
Sinn |
Selected references |
21mm |
Specific tool watch models |
|
Various |
Vintage military watches |
21mm |
German and Swiss military issued |
|
Various |
Vintage sport watches (1970s–80s) |
21mm |
Various manufacturers |
Always verify your lug width before ordering. Many watches that appear to be 21mm are actually 20mm or 22mm — measure with a digital caliper or look up your exact reference.
What Makes a Great 21mm Strap?
At 21mm, you're typically dressing a sport or tool watch with a moderately large case. The strap should be substantial enough to suit the case without being heavy-handed.
-
Taper: 21/18mm is the most common and practical. 21/19mm gives a more uniform look that suits bolder case designs.
-
Leather weight: Medium to heavy leathers suit 21mm best. Lightweight dress leathers can look incongruous on larger case sizes.
-
Pull-up leathers: Particularly good at 21mm — the wider surface area shows the patina effect well.
JackCoHenry's Top Leather Picks for 21mm
Chromexcel (Horween, USA)
- Tannery: Horween Leather Co., Chicago
- Character: Dual-tanned pull-up calf with distinctive patina development. The grain lines and colour shift that develop with wear are especially visible on wider straps.
- Best for: Breitling Navitimer, tool watches, watches worn for sport or outdoor use.
Dollaro (Conceria Walpier, Italy)
- Tannery: Conceria Walpier, Tuscany
- Character: Durable pebble-grained calf. Holds shape across conditions. Good all-round leather for watches worn heavily.
- Best for: Daily wear on sport watches. Resists the marking that smooth leathers show at 21mm.
Andria (Italian Calfskin)
- Tannery: Italian tannery
- Character: Smooth natural-grain calf with wide colour availability. Versatile across dress and casual contexts at 21mm.
- Best for: Watches that cross dress/sport lines — IWC Aquatimer on a smart-casual rotation.
El Vaquero (La Perla Azzurra, Italy)
- Tannery: La Perla Azzurra, Italy
- Character: Italian pull-up calf. Slightly softer feel than Chromexcel, warmer colour tones.
- Best for: Mid-sized sport watches where a pull-up leather suits the aesthetic but Chromexcel is too bold.
Frequently Asked Questions
Q. Is 21mm the same as 20mm or 22mm — can I use either?
No. Strap lug width must match exactly. A 20mm strap is 1mm narrower and will leave gaps at the lug edge; a 22mm strap will not fit between 21mm lugs at all. There is no acceptable adjacent size.
Q. Why do so few brands make 21mm straps?
Volume. Most strap production focuses on 18mm, 20mm, and 22mm — the sizes covering the broadest market. 21mm requires a separate cut, a separate buckle, and lower sales volume, so most production brands skip it. Bespoke and small-batch makers fill the gap.
Q. Can I verify my lug width at home without a caliper?
The most reliable method is a digital caliper. If you don't have one, a millimetre ruler held carefully across the inside of the lugs can give a rough reading. Alternatively, contact us with your exact watch reference and we'll confirm the correct size before you order.
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→ Watch Strap Size Guide: How to Find the Right Lug Width