Most watches are finished when they leave the factory. The Pasha 38 is not. Cartier gave this one a removable steel grid that clips over the dial, a crown cap on a little chain with a blue spinel cabochon set into it, and a bezel you can turn — a watch built out of parts its owner is meant to handle. Take the grid off and it is a clean silvered Arabic dial. Put it back on and it is the most recognisable Pasha there is.
That is worth keeping in mind before you change anything else on it, because it tells you what kind of watch you own. The W31040H3 was designed to be reconfigured. Swapping the bracelet for a strap is not a modification of Cartier's idea — it is the same idea, one step further.
Here is the correct size, the trap that costs people a return, and the leather that suits it.
Cartier Pasha W31040H3 Strap Size and Fit
For the Cartier Pasha W31040H3:
- Model: Pasha 38, automatic, steel
- Case: round, 38 mm, unidirectional bezel with engraved Arabic numerals
- Dial: silvered with Arabic numerals, luminescent diamond-shaped rhodium-plated hands, date between 4 and 5
- Crown: protective screw-on cap, chained to the case, set with a blue spinel cabochon
- Strap size: 20 mm at the lugs, tapering to 12 mm at the buckle
So when you order, select the 20 mm / 12 mm option.
The trap: Pashas are not all the same size
This is where Pasha owners lose money, and it is worth spelling out because the case sizes are close enough that people guess:
- Pasha C, 35 mm → 18 mm / 10 mm
- Pasha 38 mm (this watch) → 20 mm / 12 mm
- Pasha 42 mm → 21 mm / 15 mm
Three sizes, three straps, and a watch family where every model shares the same round case, the same crown cap and the same visual language. Go by your reference number, not by eye.
One more exclusion worth being straight about: the Pasha de Cartier relaunched in 2020 uses Cartier's QuickSwitch fitting, which is a completely different attachment system. Our Pasha straps are made for the classic generation — the W31 references and their contemporaries. If your Pasha has the modern tool-free release, these are not the straps for it.
Why the taper matters
The 20 mm / 12 mm shape is not a styling choice. The classic Pasha's lugs sit centrally on a round case, and the strap has to narrow sharply to clear them and to meet Cartier's folding buckle correctly. A straight 20 mm strap cut for a normal watch will foul the lugs and sit proud of the case.
Helvetus Pasha straps are cut to the 20/12 profile with shaped ends that follow the curve of the case, and they are compatible with your original Cartier Pasha folding buckle — so if you have the deployant, it carries straight over and the watch keeps its factory closure.
Why This Watch Rewards a Strap
The Pasha has always been the Cartier you were allowed to use. The line goes back over eighty years to a round, water-resistant case with a screw-down back and a capped crown, and every design decision on the W31040H3 follows from that: the cap on its chain, the screwed-down back, the grid protecting the crystal. This is not a watch that asks to be kept in a drawer.
The steel bracelet is the most conservative thing about it. On leather the 38 mm case reads warmer and slimmer, the silvered dial stops competing with a wall of polished links, and — this is the part people underestimate — the grid finally has something to stand out against. On the bracelet, steel grid over steel case over steel bracelet is a lot of one material. On a dark strap, the grid reads as the deliberate piece of design it is.
There is also a practical argument. Many W31040H3s on the market today are sold without the grid, because it comes off and gets lost. If you still have yours, the watch has two distinct looks already. Add two straps and you have four, all in about a minute each.
The Best Straps for the Cartier Pasha W31040H3
The watch gives you steel, a silvered dial, black Arabic numerals — and exactly one point of colour, the blue cabochon in the crown cap. The picks below work off that.
Blue Leather – the watch's only colour, made visible
Cartier put one colour on this watch and then hid it under a cap most people never look at. A blue strap pulls that cabochon out and makes it read as a decision rather than a detail, and deep blue against a silvered dial is one of the most flattering combinations in the whole Cartier catalogue. It suits the Pasha's water-going history too. If you buy one strap for this watch, buy this one.
→ Blue leather strap for Cartier Pasha (select 20 mm)
Black Leather – the one it will live on
The default, and there is a reason it is the default. Black gives the silvered dial maximum contrast, makes the grid the sharpest object on the watch, and takes the Pasha anywhere from a meeting to a dinner without a second thought. It is the strap most owners end up wearing four days out of five, whatever else is in the drawer.
→ Black leather strap for Cartier Pasha (select 20 mm)
Brown Leather – the 2000s Pasha, properly done
Brown on steel is the look this generation of Pasha wore best, and it is still the one that ages most gracefully. It warms the case, softens the sportiness of the bezel and turns a 38 mm steel watch into something closer to a dress piece. Pair it with a rose gold or steel buckle depending on how loud you want it.
→ Brown leather strap for Cartier Pasha (select 20 mm)
White Leather – for the half of the year that deserves it
Bolder, and completely in character. The Pasha was born as a watch for sun and water, and white leather against a silvered dial and a steel grid is about as close as you get to wearing that story on your wrist. It is a summer strap, it is not subtle, and on this particular watch it works.
→ White leather strap for Cartier Pasha (select 20 mm)
Red and pink are cut to the same 20/12 profile if you want something further out — see them all in the Cartier Pasha strap collection.
Quick Recap
- Cartier Pasha W31040H3 → 20 mm at the lugs, 12 mm at the buckle
- Pasha C 35 mm → 18/10 · Pasha 42 mm → 21/15
- Works with your original Cartier Pasha folding buckle
- Not compatible with the 2020-onwards QuickSwitch Pasha
- A strap installation tool is worth having if you plan to rotate
For the 21 mm models, see the Cartier Pasha W31077U2 strap guide. Every reference we cover sits in the Cartier strap guide index.
Cut for One Watch, Not One Size
A 20 mm strap and a 20/12 Pasha strap are not the same object, and on this watch the difference is visible from across a table. Every Helvetus Pasha strap is cut to the profile the case actually needs, in premium leather, with your choice of buckle finish — and it works with the Cartier folding buckle you already own.
More than 50,000 customers worldwide, free shipping and free returns, and no import costs on any order, from any country. Leather straps are covered by a one-year warranty.
