How Big Is a Tissot PRX? 35mm vs 40mm, Explained by a Watch Shop
Short answer: the Tissot PRX comes mainly in 35mm and 40mm. The 40mm quartz is 10.4mm thick and the Powermatic 80 automatic is a hair thicker, about 10.9mm.
Because the bracelet is built into the case, the PRX wears bigger than its diameter. As a rough guide, wrists under about 16.5cm (6.5in) usually look better with the 35mm. Above about 17cm (6.75in), most people pick the 40mm.
This is one of the questions we hear most at the counter, usually from someone holding a PRX photo on their phone. On a screen every PRX looks the same size. On a wrist they really don't. Here is what we tell people.
Tissot PRX sizes at a glance
| Model | Case | Movement | Reference starts with |
|---|---|---|---|
| PRX 35mm Quartz | 35mm | Quartz | T137.210 |
| PRX 35mm Powermatic 80 | 35mm | Automatic, 80-hour reserve | T137.207 |
| PRX 40mm Quartz | 40mm, 10.4mm thick | Quartz | T137.410 |
| PRX 40mm Powermatic 80 | 40mm, about 10.9mm thick | Automatic, 80-hour reserve | T137.407 |
| PRX Chronograph | 42mm, noticeably thicker | Automatic chronograph | T137.427 |
Every PRX above is water resistant to 100m and has a sapphire crystal. The reference number is printed on the case back, so it is a quick way to confirm which version you are looking at.
Why the PRX wears bigger than its size
Most watches have lugs that curve down around your wrist and a strap that bends right away. The PRX doesn't. The case is flat, and the first link of the bracelet is fixed solid to it. That makes the watch act like one long, rigid piece across the top of your wrist.
So a 40mm PRX covers more of your wrist than a regular 40mm watch. If your wrist is on the flat, narrow side, that first link can stick out past the edges. That is the sign the size is too big.
35mm or 40mm: who each one suits
Pick the 40mm if
- your wrist is about 17cm (6.75in) or larger
- you like a watch that is easy to read at a glance
- you want the classic PRX look most people picture, with the bold waffle dial
Pick the 35mm if
- your wrist is smaller, or flat on top
- you wear shirts with fitted cuffs and want the watch to slide under them
- you like the vintage proportions of 1970s watches, which were smaller than today's
One thing to clear up: the 35mm is not a "women's" PRX. Plenty of men wear it, and it looks great on them. Tissot sells both sizes as unisex.
A quick test you can do at home
Cut a strip of paper 40mm wide (about 1.6in). Lay it across the top of your wrist where you wear a watch. If the edges of the strip go past the flat top of your wrist and start to curve down the sides, try the 35mm. If there is room left on both sides, the 40mm will sit nicely.
THE WATCHES IN THIS ARTICLE
Sizing the bracelet
The integrated bracelet is half the reason people buy a PRX, but it has to be sized properly. The links come out with small pins or screws, depending on the model. Many PRX bracelets have no tool-free micro-adjustment, so getting the number of links right makes a real difference to comfort. If you are between two link counts, the looser fit usually feels better by the afternoon, when wrists swell a little.
Several PRX models also have a quick-release system, so you can swap the bracelet for a strap without tools. Check the exact reference before you buy if that matters to you.
Questions we get asked
Is the 40mm PRX too big for a small wrist?
Often, yes. Because of the integrated bracelet, a 40mm PRX can overhang a wrist under about 16cm. Try the paper test above, or try both sizes on in store.
Is the Powermatic 80 thicker than the quartz?
Slightly. The 40mm quartz is 10.4mm and the automatic is about half a millimetre thicker. You won't notice it under a sleeve.
Can I swim with a PRX?
Yes. The PRX is water resistant to 100m, which is fine for swimming. Just make sure the crown is pushed all the way in, and rinse it with fresh water after the pool or the ocean.
Is the PRX a good everyday watch?
It is one of the best at its price. It's tough, it goes with almost anything, and the sapphire crystal resists scratches.
Still unsure? Come try both sizes at our boutique in Place Longueuil, or send us your wrist measurement by email and we'll tell you honestly which one we'd pick.