There are three different 36 mm steel Ballon Bleus, they look almost identical in a photograph, and only one of them is this one.
The W6920046 is the classic-generation automatic: 36.6 mm steel case, silvered guilloché opaline dial with painted black Roman numerals, blued-steel sword hands, the fluted crown and its blue spinel cabochon under the guard, and Cartier's calibre 076 turning behind a domed sapphire crystal. Look closely at the VII and you will find the secret Cartier signature hidden in the numeral — a detail the brand has been quietly putting on its dials for decades.
It is the version most people mean when they say "Ballon Bleu 36", and getting a strap for it is simpler than for the newer one — as long as you know which one you have.
Lug Width: the W6920046 takes an 18 mm strap
On the product page, select the 18 mm option.
The 36 mm Ballon Bleu case uses an 18 mm strap. That figure holds across independent strap-size charts for the 36, the original Cartier strap dimensions for this case, and the 18 mm size we stock for the model.
The important part for this reference is the attachment. The W6920046 comes from the generation before Cartier introduced the interchangeable bracelet system on the current steel Ballon Bleus, which means it uses standard spring bars. No proprietary fitting, no adapter, no trip to a boutique — a spring bar tool or our installation tool and the job takes a couple of minutes.
Make sure you have this 36, not one of the others
This is where orders go wrong on the Ballon Bleu more than anywhere else:
| 36 mm model | How to tell | Strap |
|---|---|---|
| Classic automatic (W6920046) | Automatic, secret signature at VII, conventional bracelet endlinks | 18 mm, spring bars |
| Classic quartz | Same case, quartz movement | 18 mm, spring bars |
| Current generation | Bracelet detaches by a release under the endlink | 18 mm, but the bracelet uses Cartier's own interchange system |
All three take an 18 mm strap. What changes is how the bracelet comes off — so if yours does not release with a spring bar tool, you are on the current generation, not this one.
The Ballon Bleu size ladder
| Case | Strap size |
|---|---|
| 42 mm | 20 mm |
| 36 mm (W6920046) | 18 mm |
| 33 mm | 16 mm |
| 28 mm | 14 mm |
Why the curve of the case decides the strap
The Ballon Bleu is built out of curves. The case is convex in both directions, the crystal is domed, and the lugs are short and pulled inward so the whole thing reads as a pebble rather than a disc. It is the reason the watch looks the way it does — and the reason a generic 18 mm strap never quite works on it.
A straight-cut strap end meets a curved case along a single point and leaves a visible wedge of daylight on either side. On a watch whose entire design argument is continuity of line, that gap is the first thing you notice. Straps made for the Ballon Bleu are cut to follow the curve, so the leather starts where the case ends.
There is also the bracelet to think about. Polished steel centre links pick up hairlines faster than any other part of a Ballon Bleu, and they are the part that makes a used one look used. Time on a strap is time the bracelet spends in a drawer, unmarked.
The four best straps for the W6920046
1. Blue leather — the colour the watch is named after
Blue Leather Strap for Cartier Ballon Bleu
The Ballon Bleu takes its name from the blue cabochon in the crown, and the hands are blued steel to match it. On the bracelet those two details are small and easy to miss. On a blue strap they suddenly make sense — the watch stops being a silver watch with a blue stone in it and becomes a blue watch. It is the most fitting choice for this reference and, on a 36 mm case, it stays elegant rather than loud.
2. Black crocodile — the dress version
Black Crocodile Strap for Cartier Ballon Bleu
Black against a silvered guilloché dial is maximum contrast, which is exactly what makes the dial's texture readable. Crocodile adds a second texture that answers the guilloché instead of flattening it, and it lifts the watch several steps in formality without changing anything about how it wears. This is the strap for evenings and for photographs.
3. Brown leather — the one you will actually wear most
Brown Leather Strap for Cartier Ballon Bleu
Steel and a silver dial can read cold. Brown warms the whole watch and takes it out of the office without making it casual — it is the strap that turns a Ballon Bleu into something you put on without thinking about the occasion. Consistently one of the most-bought colours across the collection, and it suits the 36 better than any other size.
4. Black leather — quiet and unarguable
Black Leather Strap for Cartier Ballon Bleu
The same formality as the crocodile with none of the texture and none of the attention. Smooth black leather is the most versatile strap you can put on this watch, it never looks wrong, and it is the safest first purchase if you are replacing a tired original and want the watch to look right immediately.
Every colour and size is in the Cartier Ballon Bleu strap collection.
Fit, in one line
Order 18 mm, choose a buckle finish, and fit it with standard spring bars.
More Cartier strap guides
Cut for the curve
Helvetus straps are made for one watch at a time. Our Ballon Bleu straps are shaped for the case in 14 mm, 16 mm, 18 mm and 20 mm, so the leather meets the curve of the case cleanly instead of leaving the gap a generic band always leaves.
More than 50,000 customers worldwide, free shipping and free returns, and no import costs on any order, anywhere. Leather straps are covered for one year; our rubber straps carry a lifetime warranty.
