Circula band size chart by model class
Circula is a Pforzheim maker, Circula Uhren GmbH, that sells direct through its own en-US shop [1], and its product pages print something almost no one else does: a properties table with a Max. Arm circumference row, the largest wrist the watch fits as delivered, printed per strap option [7]. We pulled the entire current en-US catalog fresh at build time, all 92 watch references and all 29 straps, every page HTTP 200 [1][6]. Headline: the lug width is 20 mm on every single watch, so the strap-width question is trivial and the real sizing decision is the fit matrix underneath it: diameter, length over lugs, height, and that arm-circumference ceiling per strap option. No consolidated chart of this exists elsewhere: watchbands.ai's index of 202 brands carries no Circula entry [23] and both build-time chart searches returned zero organic results [24][25].
The fit matrix: 8 model classes, one lug width, three case sizes
| Model class | Refs | Diameter | Length over lugs | Height | Lug width | Max. Arm circumference |
|---|---|---|---|---|---|---|
| AquaSport II [7] | 19 | 40 mm (without crown) | 46 mm | 12.6 mm without glass; 13.4 mm with glass | 20 mm | 21 cm on the tropical rubber strap, 22 cm on the steel strap |
| AquaSport GMT [8] | 4 | 40 mm (without crown) | 46 mm | 12.6 mm without glass; 13.4 mm with glass | 20 mm | 21 cm on the tropical rubber strap, 22 cm on the steel strap |
| ProSea [9] | 12 | 40 mm (without crown) | 46 mm | 11.7 mm without crystal, 12.9 mm incl. crystal | 20 mm | 21 cm on hybrid rubber strap, 22 cm on steel bracelet |
| ProTrail Power+ [10] | 10 | 40 mm (without crown) | 46 mm | 11 mm without glass; 12.3 mm with glass | 20 mm | 21 cm on the canvas strap, 22 cm on the steel strap |
| ProFlight Power+ [11] | 6 | 40 mm (without crown) | 46 mm | 11 mm without glass; 12.3 mm with glass | 20 mm | 21 cm on the canvas strap, 22 cm on the steel strap |
| ProFlight Black [12] | 2 | 40 mm (without crown) | 46 mm | 12 mm without glass; 13.3 mm with glass | 20 mm | 21 cm on the canvas strap, 22 cm on the steel strap |
| Facet 38 (incl. Guilloche LE) [13] | 26 | 38 mm (without crown) | 44.5 mm | 9.9 mm | 20 mm | 20 cm on leather strap, 22 cm on steel bracelet |
| Facet 41 [14] | 12 | 41 mm (without crown) | 47.6 mm | 10.4 mm | 20 mm | 20 cm on leather strap, 22 cm on steel bracelet |
Every cell in the diameter, length, height, lug width and arm-circumference columns is the verbatim string the class's own product page prints in its properties table, quoted from a fresh en-US pull at build time [7]. Nothing is converted, rounded or inferred. Two print conventions run through the catalog: the dive and field classes print height twice, without and with glass or crystal, while both Facet classes print a single height figure. And every diameter is printed without crown, so the watches wear smaller than a crown-inclusive listing would suggest.
The count column adds to 91 of the 92 references, because the 92nd is the one watch that refuses a single row: the ProLab, a two-variant collaboration with fellow Pforzheim brand Laco, prints its properties per variant and gets its own table below [15].
The ProLab split: one page, two watches, two fits
The ProLab page is the only en-US product page that prints no Lug Width row in a standard properties block [15]. Instead its properties list splits every dimension by variant name, Sand and Schwarz, and the two variants are different watches for wrist purposes:
| ProLab variant | Diameter | Length over lugs | Height | Max. Arm circumference | Weight |
|---|---|---|---|---|---|
| Sand [15] | 40 mm | 47,5 mm | 9.8 mm without crystal, 11.3 mm incl. crystal | 20,5 cm on Sailcloth strap | 72 g with Sailcloth strap |
| Schwarz [15] | 40 mm | 46 mm | 11.1 mm without crystal, 12 mm incl. crystal | 21 cm on Sailcloth strap | 85 g with Sailcloth strap |
Two details to read carefully. First, the decimal commas: this en-US page still prints 47,5 and 20,5 in German notation, quoted here exactly as the bytes come back [15]. Second, the description text above the properties list confirms the same numbers in prose, 40 mm in diameter, 46 mm lug to lug, so the Schwarz variant carries the standard 40mm-class footprint while the Sand runs half a millimeter longer over the lugs and half a centimeter tighter on the wrist [15]. Neither variant prints a lug width row anywhere on the page, so a ProLab owner buying a third-party strap measures the gap rather than trusting a width that was never printed; the brand's own sizing guide says many Circula models feature a 20-mm lug width without committing to this one [27].
The wrist-fit rail: what Max. Arm circumference actually buys you
This row is why the Circula catalog charts better than most. Where every other brand makes you infer fit from lug-to-lug and hope, Circula prints the ceiling [7]. The pattern across all 91 spec-table references is perfectly regular: 20 cm on the leather and suede straps of the Facet classes, 21 cm on the canvas, tropical rubber and hybrid rubber straps of the sport classes, and 22 cm on every steel bracelet in the catalog [7][9][10][13]. The ProLab Sand splits the difference at 20,5 cm [15].
The purchase consequence is concrete: the strap option moves your fit window a full centimeter, which is more than the case-size differences between classes do. A 21.5 cm wrist gets no closure on any factory Circula strap except a steel bracelet, regardless of whether the watch is a 38mm Facet or a 40mm AquaSport II [7][13]. Conversely, small wrists are served by strap lengths the brand prints on its own strap pages: 72 and 114 mm on the suede, 75 and 115 mm on the smooth leather, 75 and 120 mm on canvas, and a longer 80 and 130 mm cut on some tropical rubber colorways [16][17][19][20].
The 20mm strap catalog: tapers, lengths and one typo
Since every watch takes 20mm, the strap pages are where the sizing detail lives. All 29 current strap product pages were pulled fresh [6], and they print their own properties tables:
| Strap (representative page) | Band width as printed | Thickness | Length without clasp | Material as printed |
|---|---|---|---|---|
| Sailcloth, DLC black [16] | 20 mm at the lugs, 18 mm at the buckle | 3 mm | 75 & 120 mm | Nylon canvas and genuine leather on the inside |
| Tropical rubber, black [17] | 20 mm at the lugs, 18 mm at the buckle | 3 mm | 80 & 130 mm | EPDM-type tropical rubber |
| Tropical rubber, blue [18] | 20 mm tappering | 3 mm | 75 & 120 mm | same strap family, colorway page |
| Suede leather, brown [19] | 20 mm at the lugs, 18 mm at the buckle | 3,5 mm | 72 & 114 mm | Suede calfskin, vegetable tanned (not chemically sealed) |
| Smooth leather, black [20] | not printed | 3 mm | 75 & 115 mm | Smooth calfskin, vegetable tanned (not chemically sealed) |
| Steel bracelet, ProTrail / ProFlight [21] | 20 mm at the lugs, 18 mm at the buckle | 4 mm | not printed | 316L stainless steel, scratch-resistant |
Three quirks worth knowing before you shop. The tropical rubber family prints the full taper sentence, 20 mm at the lugs, 18 mm at the buckle, on its black and navy colorway pages but the words 20 mm tappering on six other colorways, a typo the brand has left in place, quoted here as printed [17][18]. The smooth leather strap is the one strap page that prints no Band width row at all, flagged here rather than guessed [20]. And the steel bracelet for the Pro series comes in two products, the current one and a separate listing for ProTrail and ProFlight watches until 2025, so pre-2026 owners check which bracelet generation their watch takes before ordering [21]. The steel, titanium and beads-of-rice bracelet pages print no strap length because their length is links, not millimeters.
One width, three cases: why the matrix still matters
A one-width brand risks a boring chart, and Circula is anything but. The 20mm lug width spans a 38mm x 44.5mm Facet 38 at 9.9mm thick and 95 g on leather, and a 40mm x 46mm AquaSport II at 13.4mm with glass and 155 g on its bracelet [7][13]. That is a 3.5mm thickness spread and a 60 gram bracelet-weight spread on identical strap width, which is the difference between a watch that disappears under a cuff and one that will not clear it. The height print convention matters here too: the sport classes print with and without glass because their double-domed crystals add more than a millimeter, so check which figure a forum post is quoting before you compare [7].
For strap buyers the uniform width is pure upside: one 20mm strap inventory serves the whole catalog, and the brand's own 29-strap store means cross-family mixing is a first-party option, a Facet 38 on the Pro-series steel bracelet or an AquaSport II on suede, as long as your wrist fits the printed ceiling for that pairing [6].
How this catalog was counted
The en-US shop at circulawatches.com/us/ is a Shopware store, not Shopify, so there is no products.json feed; the catalog was enumerated from the shop's own category listings instead. The all-watches listing carries 92 watch product URLs [1], spread across the dive [2], field [3], pilot [4] and steel-sport [5] categories, and the straps listing carries 29 [6]. All 121 pages were pulled fresh en-US at build time, every one HTTP 200, and 91 of the 92 watch pages print the full five-row properties table with identical values inside each model class, verified by grouping all 92 spec signatures [1]. The German-language sitemap the shop publishes, 220 URLs, cross-checks the same catalog shape [22]. Colorway references within a class, like the eleven AquaSport II dials or the steel-versus-strap bundle SKUs, share their class row exactly; no reference inside a class deviated by even a decimal.
Why no one else has this chart
The incumbent check ran at build time, two methods. watchbands.ai, the largest strap-size database, lists 202 brands with its seiko, citizen and rolex entries all present and no Circula entry by slug or by text [23]. Bing returned zero organic results for the consolidated-chart queries [24][25], and the second-engine sweep surfaced only the brand's own pages and generic strap-sizing guides [26]. The nearest thing that exists is the brand's own blog guide, Finding the Right Watch Size, which confirms in prose that many Circula models feature a 20-mm lug width without tabling a single model [27]. Every row on this page cites the exact product page it was pulled from, and the one spec the brand does not print anywhere, the ProLab lug width and the smooth-leather strap width, is flagged not printed rather than inferred.
Related guides
- Watch band size chart: the full brand-by-brand index this page extends.
- Lug width chart by brand: where Circula sits in the one-width brand table.
- How to measure: for ProLab owners, whose lug width no page prints.
- Watch strap taper chart: the second number in listings like 20/18, which Circula's own straps print as 20 at the lugs, 18 at the buckle.
Sources
- circulawatches.com en-US all-watches listing (92 watch product URLs enumerated; fresh en-US pull at build, http 200): circulawatches.com/us/watches/all-watches
- circulawatches.com en-US dive-watches category (fresh en-US pull at build, http 200): circulawatches.com/us/watches/dive-watches
- circulawatches.com en-US field-watches category (fresh en-US pull at build, http 200): circulawatches.com/us/watches/field-watches
- circulawatches.com en-US pilot-watches category (fresh en-US pull at build, http 200): circulawatches.com/us/watches/pilot-watches
- circulawatches.com en-US sport-watches category, steel-sport Facet class (fresh en-US pull at build, http 200): circulawatches.com/us/watches/sport-watches
- circulawatches.com en-US straps listing (29 strap product URLs enumerated; fresh en-US pull at build, http 200): circulawatches.com/us/straps
- circulawatches.com en-US product page: AquaSport II Blue, properties table verbatim (fresh en-US pull at build, http 200): circulawatches.com/us/watches/dive-watches/aquasport-ii-blue/ae-st-bb
- circulawatches.com en-US product page: AquaSport GMT Blue, properties table verbatim (fresh en-US pull at build, http 200): circulawatches.com/us/watches/dive-watches/aquasport-gmt-blue/ag-st-bb
- circulawatches.com en-US product page: ProSea Anthracite, properties table verbatim (fresh en-US pull at build, http 200): circulawatches.com/us/watches/dive-watches/prosea-anthracite/ps-sh-as
- circulawatches.com en-US product page: ProTrail Power+ Black, properties table verbatim (fresh en-US pull at build, http 200): circulawatches.com/us/watches/field-watches/protrail-power-black/pt-ss-ss
- circulawatches.com en-US product page: ProFlight Power+ Anthracite, properties table verbatim (fresh en-US pull at build, http 200): circulawatches.com/us/watches/pilot-watches/proflight-power-anthracite/pf-ss-as
- circulawatches.com en-US product page: ProFlight Black, properties table verbatim (fresh en-US pull at build, http 200): circulawatches.com/us/watches/pilot-watches/proflight-black/pf-ds-ss
- circulawatches.com en-US product page: Facet 38 Anthracite, suede strap, properties table verbatim (fresh en-US pull at build, http 200): circulawatches.com/us/watches/steel-sports-watches/facet-38-anthracite-suede-strap/fs-sv-ss
- circulawatches.com en-US product page: Facet 41 Anthracite, suede strap, properties table verbatim (fresh en-US pull at build, http 200): circulawatches.com/us/watches/steel-sports-watches/facet-41-anthracite-suede-strap/fs-41-sv-ss
- circulawatches.com en-US product page: ProLab (Laco collaboration), per-variant properties list verbatim incl. German decimal commas (fresh en-US pull at build, http 200): circulawatches.com/us/watches/field-watches/prolab/pl-ss-ss
- circulawatches.com en-US strap page: Sailcloth Strap Black DLC, properties verbatim (fresh en-US pull at build, http 200): circulawatches.com/us/straps/sailcloth-strap-black-dlc/ds-s
- circulawatches.com en-US strap page: Tropical Rubber Strap Black, properties verbatim (fresh en-US pull at build, http 200): circulawatches.com/us/straps/tropical-rubber-strap-black/st-s
- circulawatches.com en-US strap page: Tropical Rubber Strap Blue, prints 20 mm tappering (fresh en-US pull at build, http 200): circulawatches.com/us/straps/tropical-rubber-strap-blue/st-b
- circulawatches.com en-US strap page: Suede Leather Strap Brown, properties verbatim (fresh en-US pull at build, http 200): circulawatches.com/us/straps/suede-leather-strap-brown/sv-u
- circulawatches.com en-US strap page: Leather Strap Black without stitching (no Band width row printed; fresh en-US pull at build, http 200): circulawatches.com/us/straps/leather-strap-black-without-stitching-silver/sl-s
- circulawatches.com en-US strap page: Steel Bracelet for ProTrail / ProFlight, properties verbatim (fresh en-US pull at build, http 200): circulawatches.com/us/straps/scratch-resistant-steel-bracelet-for-protrail-proflight/sk-s
- circulawatches.com Shopware sitemap child, de locale (220 URLs, catalog cross-check; fresh pull at build, http 200): circulawatches.com/sitemap.xml
- watchbands.ai brand index, fresh pull at build (202 brands, controls seiko/citizen/rolex present, no Circula): watchbands.ai/brands
- Bing search: circula band size chart (zero organic results, b_no): www.bing.com/search?q="circula"+band+size+chart
- Bing search: circula lug width guide (zero organic results, b_no): www.bing.com/search?q="circula"+lug+width+guide
- Second-engine SERP sweep at build (brand pages and generic strap-sizing guides only; no consolidated chart): web_search method-A sweep, logged in build notes
- circulawatches.com blog: Finding the Right Watch Size (confirms 20-mm lug width across many models in prose; fresh pull at build, http 200): circulawatches.com/us/blog/Finding-the-Right-Watch-Size