The Tudor Black Bay 36 (Ref. 79640) is one of those watches that quietly does everything right. It’s got the Black Bay family look, but without the bulk, without the “tool watch costume.” Just a clean, compact daily wearer that can look sharp in a hoodie or under a cuff.
I’ve seen people buy this watch as their first “proper” Tudor, and I’ve also seen collectors keep it around even after bigger, louder pieces come and go. That tells you a lot. The size is the secret. 36mm feels intentional here, not like a compromise, and the watch has enough presence to avoid looking vintage-small.
Strap size and fit guide for the Black Bay 36 (79640)
Let’s keep you from ordering the wrong thing.
Your Tudor Black Bay 36 Ref. 79640 is a 36mm case with a 19mm lug width. That 19mm is the detail that catches people out because plenty of Tudors sit on 20mm, but this one doesn’t.
When you’re on Helvetus product pages, make sure you select “Black Bay 36” as the model option before adding to cart. Don’t pick “Black Bay 58,” don’t pick “Black Bay 41,” don’t guess. The Black Bay line is full of watches that look similar in photos but fit completely differently at the lugs, and the last thing you want is a strap that’s almost right.
If you remember two things, remember this: 36mm case, 19mm lugs. Then choose Black Bay 36 on the product page.
The best strap choices for the Tudor Black Bay 36
The Black Bay 36 is basically a blank canvas, and that’s why it’s so easy to make it feel like a different watch with the right color. The case proportions are tidy, the dial is clean, and the whole watch sits close to the wrist, so strap color does a lot of the heavy lifting.
Navy Blue is the one I keep coming back to when someone wants the watch to feel a bit more “Tudor.” It’s not loud, but it adds depth, especially if your Black Bay 36 has that crisp, minimal dial that can otherwise feel a little too monochrome. Navy also plays nicely with the polished accents on the watch without making it look dressy. It’s the strap that makes the Black Bay 36 feel sporty in a grown-up way.
Tudor Black Bay Navy Blue Rubber Strap
White sounds risky until you see it on a 36mm case. On larger dive watches, white can scream summer-only. On the Black Bay 36, it looks clean and modern, almost like a designer sneaker effect on the wrist. If your dial is black, the contrast is perfect, and the smaller case keeps it from looking flashy. This is the strap for warm weather, weekend wear, and that “fresh out of the box” look even when the watch is your daily.
Tudor Black Bay White Rubber Strap
If you want something with a bit more personality without going into bright colors, the Black with White line LuxLine® is a smart move. The line gives the watch a more technical, performance feel, almost like it’s leaning back toward the Black Bay’s tool-watch roots, but it still stays clean because it’s just one detail, not a full color explosion. It also works strangely well when you’re wearing neutral outfits, because the strap has its own “design language” without demanding attention.
Tudor Black Bay Black/White LuxLine Rubber Strap
And here’s the nice part: once you know the fit is right, you can rotate colors depending on mood. The Black Bay 36 doesn’t fight you. If you want to see more options beyond these three, you’ll find a full range of colors here:
All Tudor Black Bay Rubber Bands
Buying the right strap from Helvetus
With the Black Bay 36, precision matters because of that 19mm lug width and the way the case hugs the strap. The good news is it’s simple: choose a strap made for this line, then select Black Bay 36 on the product page so you’re matching the correct fit.
If you’re the type who likes to change the personality of a watch without changing the watch, this is exactly the kind of Tudor that rewards it. Start with one color you’ll wear constantly, then add a second that feels different enough to justify the swap. The collection page makes it easy to browse what suits your style without overthinking it.
https://helvetus.com/collections/tudor-black-bay-straps
Closing thoughts
The Tudor Black Bay 36 Ref. 79640 is already a strong everyday watch, but the right strap makes it feel more personal, more “yours.” And when the strap is designed to fit this specific model properly, you get the clean look you want without awkward gaps or guesswork. Helvetus keeps it simple: you get a lifetime warranty, free worldwide shipping, no import costs, and a fit that’s made for the Black Bay 36 when you select the correct option. It’s also one of those purchases that feels low-risk because you’re buying from a brand trusted by over 30,000 customers worldwide, and you can tell it’s built for real daily wear, not just photos.
