Short answer: WSSA0009 and WSSA0018 are the same watch. Both denote the Santos de Cartier Large model in stainless steel, 39.8 mm by 47.5 mm, automatic calibre 1847 MC, 100 metres of water resistance, supplied with a steel bracelet and a calfskin strap on the QuickSwitch system. WSSA0018 is the reference Cartier and its authorised retailers list today. WSSA0009 is the earlier reference for the same model, and it still circulates widely in the pre-owned channel.
If you have been comparing the two listings and cannot find the difference, that is because there is no verified specification difference to find. The comparison worth making is a different one, and we set it out below.
The evidence that they are one watch
Three independent signals confirm it:
- Watches of Switzerland US serves the WSSA0018 product page and a WSSA0009 URL from the same product identifier, 17310953.
- Betteridge lists WSSA0018 as the "Santos De Cartier Watch, Large Model, Automatic Movement, Steel, Interchangeable Metal And Leather Bracelets", which is word for word the description previously carried on WSSA0009 pages.
- PrestigeTime lists WSSA0009 at 9,200 US dollars and marks it no longer available. That is the identical figure carried by WSSA0018 at authorised retail on 26 July 2026.
What we cannot tell you, because Cartier has not published it and no boutique source confirms it, is the exact date of the renumbering or the reason behind it. Anyone stating a year for that change is guessing. We will not.
Specification: Santos de Cartier Large, steel
| Attribute | WSSA0018 (and WSSA0009) |
|---|---|
| Model | Santos de Cartier, Large model |
| Case | Stainless steel, 39.8 mm wide, 47.5 mm lug to lug |
| Thickness | 9.08 mm as published at the 2018 launch. Several current retailers publish 9.38 mm. |
| Calibre | 1847 MC, in-house automatic, 28,800 vph, 23 jewels |
| Power reserve | Approximately 40 hours. 42 hours is also widely published. |
| Water resistance | 10 bar, approximately 100 metres |
| Dial | Silvered opaline, Roman numerals, blued-steel sword hands, date at 6 o'clock |
| Crown | Seven-sided, faceted synthetic spinel cabochon |
| Supplied with | Steel bracelet with folding clasp and a calfskin strap, both on QuickSwitch |
| US retail | 9,200 US dollars, observed at two authorised retailers on 26 July 2026 |
Two figures above carry a genuine conflict in the published record. Monochrome recorded 9.08 mm and 42 hours from Cartier's 2018 launch material; Betteridge currently publishes 40 hours, and Watches of Switzerland carries both numbers on a single page. We report both rather than choose one and present it as settled.
The comparison that actually matters: medium against large
If you are choosing a steel Santos rather than reconciling two references, the real fork is WSSA0029 against WSSA0018. And the step up in size brings a complication with it.
| WSSA0029, Medium | WSSA0018, Large | |
|---|---|---|
| Case | 35.1 mm by 41.9 mm | 39.8 mm by 47.5 mm |
| Thickness | 8.83 mm | 9.08 mm at launch |
| Date window | None | At 6 o'clock |
| Calibre | 1847 MC automatic | 1847 MC automatic |
| Water resistance | 100 metres | 100 metres |
| US retail, 26 July 2026 | 8,400 US dollars | 9,200 US dollars |
Eight hundred dollars of retail difference buys 4.7 mm of case width, 5.6 mm of lug to lug, and a date. For buyers who want the cleanest possible dial, the medium is not a compromise. It is the purer design.
One conflict we have not resolved: Betteridge states that the two-tone medium, W2SA0016, does carry a date, which sits awkwardly against the no-date steel medium. Confirm with the boutique before treating the medium as universally dateless.
Which size for which wrist
Bob's Watches published a size guide on 2 July 2026 giving the following split, and noting that "the tipping point between the two tends to sit around the 7-inch mark":
- Under 6.5 inches (16.5 cm): Santos de Cartier Small, or Santos-Dumont Small or Medium
- 6.5 to 7.25 inches (16.5 to 18.4 cm): Santos de Cartier Medium
- 7.25 inches and above (18.4 cm and above): Santos de Cartier Large, or Santos-Dumont XL
Treat the 47.5 mm lug to lug figure with context. The curved caseback and short, integrated lugs mean the large sits closer to the wrist than the number implies. Monochrome's review of the large model records "good comfort" despite the proportions.
QuickSwitch and SmartLink, and why they matter to a pre-owned buyer
Both systems arrived with the 2018 relaunch and are fitted to the medium and the large.
QuickSwitch is a push-button release built into the end of each strap and bracelet, not into the case. Bracelets and straps come off without a tool. SmartLink puts an oval push-piece on the underside of each bracelet link so links can be added or removed without a tool.
The practical consequence when buying pre-owned is straightforward: because the release mechanism lives in the strap rather than the case, a missing original bracelet is a materially larger gap than on a conventional lugged watch. Ask what is in the box before you ask about the price.
What we check before a Santos reaches the site
Honeyrock's vetting team is physician-led, and the discipline that comes with that background is applied to every watch in the same order every time:
- Case geometry and bevel definition against unpolished reference examples, since the Santos case is easy to soften with over-polishing
- Calibre 1847 MC serial and finishing, timing across positions, amplitude and beat error
- Bracelet link count, SmartLink function on every link, and clasp engagement
- QuickSwitch engagement on both the bracelet and the strap
- Crown spinel condition and crown thread integrity, then pressure testing
- Papers, warranty card date, and whether the reference on the card matches the case
That last point is where WSSA0009 and WSSA0018 stop being trivia. A card reading WSSA0009 on a watch presented as WSSA0018 is not a red flag. A card reading a medium reference on a large case is.
Frequently asked questions
Is WSSA0018 a newer or better watch than WSSA0009?
Neither. It is the same model under a current reference number. No verified specification difference exists between the two.
Does the Santos de Cartier Large have a date?
Yes, at 6 o'clock. The steel medium, WSSA0029, does not.
What size is the Santos de Cartier Large?
39.8 mm wide by 47.5 mm lug to lug, approximately 9 mm thick.
Can you swim with a Santos de Cartier?
The watch is rated to 100 metres. That is comfortably specified for swimming. It is not a dive watch: there is no rotating timing bezel and no ISO 6425 certification. See our guide to what water resistance ratings actually mean.
Which movement is in the Santos de Cartier?
Calibre 1847 MC, Cartier's in-house automatic, in both the medium and the large.
Why do pre-owned Santos prices vary so widely?
Three factors dominate: whether the original bracelet and strap are both present, whether the case has been polished, and whether the box and papers are complete. The reference number itself, WSSA0009 or WSSA0018, is not one of them.
Currently at Honeyrock
- Cartier Santos, Ref. WSSA0009, box and papers, extra strap
- Cartier Santos Large, Ref. WSSA0018, box and papers, active warranty
- Santos de Cartier Titanium Large 40 mm, grey dial, Ref. WSSA0089
- All Cartier at Honeyrock
Sources
- Betteridge, Santos de Cartier Large Model WSSA0018 product page, observed 26 July 2026.
- Watches of Switzerland US, WSSA0018 and WSSA0029 product pages, observed 26 July 2026.
- PrestigeTime, Cartier Santos de Cartier Large WSSA0009, observed 26 July 2026.
- Monochrome, "Cartier Santos Large 2018 review", launch specifications and comfort assessment.
- Time and Watches, "SIHH 2018: Cartier new Santos", QuickSwitch and SmartLink description.
- Bob's Watches, "Cartier Santos sizes", published 2 July 2026.
- Exquisite Timepieces, "Cartier Santos Medium vs Large", date window confirmation.
Prices stated are authorised retail figures observed on the date given and are not offers. Honeyrock Luxury does not make claims about future value or price appreciation. Last updated 26 July 2026.
