The Cartier Santos 100 Chronograph W20090X8 is the biggest, boldest expression of the Santos 100 idea. Built around a roughly 42 mm square steel case with the collection's exposed bezel screws, it adds a full chronograph to the anniversary formula: three sub-dials, a date between 4 and 5 o'clock, and serious wrist presence. Like every Santos 100, it left the boutique on a strap — black alligator, in this case — which makes strap replacement a question of when, not if, for every owner.
It is also the reference behind a sizing option that confuses a lot of Santos 100 owners, so let's settle that first.
Cartier Santos 100 Chronograph W20090X8 Strap Size and Fit
For the Cartier Santos 100 Chronograph W20090X8:
- Model: Santos 100 XL Chronograph
- Case: square, steel, approx. 42 mm with exposed bezel screws
- Attachment: standard spring bars — no QuickSwitch on this generation
- Strap width at the case: 24.5 mm
This means the watch requires a 24.5mm strap. When ordering, simply select the 24.5mm option on the product page.
For clarity, this is how the Santos 100 family maps to strap sizes: the midsize takes 20mm, the classic 38 mm model takes 23mm, and the XL Chronograph — this reference — takes 24.5mm. If you have seen the 24.5mm option and wondered which watch it belongs to, it belongs to yours. Helvetus Santos 100 straps come with spring bars included and are compatible with your original Cartier buckle.
One more note: straps made for the modern Santos de Cartier quick-release models will not fit any Santos 100, this one included. The straps below are shaped specifically for the Santos 100 case.
The Heavyweight of the Anniversary Line
The Santos 100 celebrated a century of the original 1904 design, and the Chronograph was its flagship — the version for owners who wanted the historic square case at full volume. Nearly two decades on, it has become a distinctive pre-owned pick: unmistakably Cartier, unmistakably large, and priced well below what its presence suggests.
Because it lives on a strap, that strap defines the watch. The original alligator dresses it up; a rubber strap turns the same case into a legitimate sports chronograph. Owners of the W20090X8 tend to discover that the second personality is the one they wear most.
The Best Straps for the Cartier Santos 100 Chronograph W20090X8
Helvetus offers rubber and leather straps made specifically for the Santos 100 case, including the 24.5mm Chronograph fit. You can browse every compatible option here: Cartier Santos 100 Strap Collection.
Below are the most popular choices among owners of this reference, matched to its silvered dial, black Roman numerals, and steel case.
Black Leather Strap
The like-for-like replacement for the original black alligator. It keeps the Chronograph formal and classic, frames the silvered dial cleanly, and restores the look the watch had on day one — the natural first choice when the factory strap gives out. Black Leather Strap for Cartier Santos 100
Grey Rubber Strap
Grey rubber creates a tonal, steel-on-steel effect that suits the big case surprisingly well. It reads modern and understated while making the watch fully waterproof-practical — a favorite for owners who wear the Chronograph daily. Grey Rubber Strap for Cartier Santos 100
White Rubber Strap
Few watches can carry white; the XL Chronograph is one of them. White rubber picks up the bright dial, doubles the wrist presence, and turns the W20090X8 into a striking summer piece that gets noticed for all the right reasons. White Rubber Strap for Cartier Santos 100
Orange Rubber Strap
A chronograph deserves one racing option. Orange against the steel case and silvered dial gives the Santos 100 Chronograph genuine motorsport energy — the boldest look in this guide and a signature choice among owners who bought the XL to stand out. Orange Rubber Strap for Cartier Santos 100
The collection includes further colors in leather and rubber, all shaped for the Santos 100 case.
Final Thoughts
The W20090X8 was built to be the loudest Santos in the room, and the right 24.5mm strap is what keeps it that way — dressed in leather or unleashed on rubber.
Helvetus is a leading name in aftermarket straps for luxury watches, trusted by more than 50,000 customers worldwide. Every Santos 100 strap is shaped for a precise fit, rubber straps are covered by a lifetime warranty, and all orders ship free worldwide with no import costs.
Find the perfect strap for your Santos 100 Chronograph W20090X8 in the Cartier Santos 100 Strap Collection.
