Xiaomi Watch S4 review

Introduction and unboxing

This is Xiaomi's Watch S4 and it's among the most customizable smartwatches you can get now. It comes in a single 47mm version and in three case colors - silver, grey, and black, but its case bezel can be changed on the fly, giving you practically endless options.

We have the Rainbow model, which is a shade lighter than the Black one. It comes with a unique black bezel with colorful accents and a fluororubber strap with multi-colored stitching. The watch is €170 at the time of this article.

Inside the retail box is the watch, its strap, and a 2-pin magnetic charger. The charger uses USB-A plug, which is disappointing in 2025. It's also slightly fiddly to attach the charger properly - rival watches like Samsung's Galaxy Watch and Huawei's Watch also use a proprietary charger, but it's magnetic - just plop the watch on top and forget about it.

What's inside the box

We also have the additional Dual-tone Ceramic bezel and strap kit, which completely overhauls the watch's appearance. The watch is smarter about swapping bezels, too - there's now a warning when you remove the bezel - the watch vibrates constantly until you place the bezel back on the watch. A welcome change, considering how easy it was to accidentally pop the bezel off on the Watch S3 and lose it.

The case has a bayonet-style mechanism, where the bezel locks into place.

The additional camera bezel and leather strap

Design and build quality

Even better, Xiaomi went with a standard 22mm band size, opening a world of possibilities for both third-party and Xiaomi straps. Who doesn't love variety?

There are hundreds, if not thousands, of 22mm lug watch straps on Amazon, AliExpress, and the like, in genuine leather, fake leather, rubber, ballistic nylon and more. But there are also third-party bezels for the Watch S4 already, so you can customize it to your heart's content!

The Xiaomi Watch S4 has a classic look. The bezel sits prominently on the round case and protrudes a few mm above the screen glass cover, protecting it from scratches.

The case is made of an aluminum alloy, while Xiaomi doesn't specify anything about the glass, but we'd guess it has some level of scratch resistance.

While some watches use a more hardy and premium stainless steel for the exterior, the aluminum used in the Xiaomi Watch S4 allows for a lightweight package of just 44.5g. In comparison, the OnePlus Watch 3 is 49.7g, while the Galaxy Watch6 Classic is 59g.

The screen is a huge improvement over its predecessor. It's a 1.43-inch 466x466px 60Hz unit that's brought the old 600 nits up to 2,200 nits. It's a noticeable bump - this panel will leave you wanting for nothing, even in the brightest of conditions.

There's an always-on screen mode that's tailored to each individual watch face.

There are two controls on the right side of the Xiaomi Watch S4 - one is the new rotating crown, which doubles as a pusher, and below it is another button that sits more flush with the case.

The rotating crown adds a welcome layer of control to the smartwatch. It's precise, and has a lovely vibration feedback.

The controls

The heart rate and blood oxygen combo sensor sits on the bottom of the watch (it lights up in green and red). This is also where the two pins for the magnetic charger sit.

The 1.43-inch 466x466px AMOLED display is, again, superb - crisp and bright. But it's Xiaomi's effort in making sophisticated watch faces that makes it even better. There are nine built-in faces, all high quality, all featuring a myriad of customizable widgets for different data - battery life, steps, the day of the week, etc.

Our only slight gripe is that all the watch faces are black - great for AMOLED battery endurance, sure - but we'd like a few lighter faces too. You can find a lot of additional watch faces in the Mi Fitness app, so it's all good.

The Xiaomi Watch S4 is kind of unique in that it's a large watch at 47mm, but also light. It's for the unique user who likes them big but light! The Watch S4 lends itself perfectly to the duty of a fitness or sleep tracker.

On the other hand, people who like a little heft to their watch won't be the biggest fans of this one.

Xiaomi equipped the Watch S4 with its HyperOS 2, with seamless device connection with Xiaomi's Smart Hub. A push on the crown takes you to your apps grid, another back to the main watch screen. A swipe from the top brings up the notifications, a swipe downward brings up the different widgets you have set - the activity tab, your heart rate, the weather, etc. Once you've scrolled through your widgets, you get to the apps grid.

Notifications are basic. You get a stream of floating messages that you can tap to see in full and then dismiss. You can't answer from the watch, and Messenger emojis aren't supported, so you get a weird symbol.

What's unique about the Xiaomi Watch S4 is that nothing happens when you swipe left and right on the main screen (well, a swipe left gives you a way to change the watch face) - most other smartwatches have a horizontally-scrollable interface, Xiaomi went with a vertical one.

A push on the second button opens up the quick toggles.

There are also gestures. You can rotate or shake your wrist, or snap your fingers to achieve a number of customizable actions - reject a call, take a photo (though you need to have the camera app open on your phone, and a watch camera app open on the watch too), or open the weather app. We tried them, but we can't say they work consistently.

Sadly, the physical controls aren't customizable - the crown and the button below it are set in their ways for life!

Fitness and sleep tracking, battery life

The Xiaomi Watch S4 has excellent sports and health tracking credentials, as you'd expect. To quote the one-pager, you get more than 150 sports modes - including a personal running coach, and even a professional skiing mode (a rarity on many watches).

The Watch S4 supports dual-band GPS, which uses both the wider L1 and the faster and more accurate L5 band to provide tracking accuracy within the meter. We achieved GPS lock in around 40 seconds, and the map data was very accurate.

Fitness tracking

We're happy with the fitness tracking on the Xiaomi Watch S4. The workout screen is nicely laid out with the time and the intensity of the workout front and center. We'd also say that the heart rate tracking was consistent with other brand fitness trackers.

This reviewer has never been a fan of Xiaomi watches' overzealous sleep tracking data. I get no more than 50 minutes of deep sleep per night, as established by years of daily tracking with Samsung's Galaxy Watches and Galaxy Ring, Huawei's GT and Fit series - none of those have ever given me more than an hour of deep sleep per night. Xiaomi's watches estimate that I consistently get more than 2 hours of deep sleep per night.

Yes, it's true that outside of lab testing, sleep tracking is mostly estimation-based, but more than 2 hours of deep sleep is bonkers for the fittest of persons.

Nitpick aside, Xiaomi's sleep tracking is engaging, giving you interesting metrics comparing your sleep to other users, assigning you a sleep animal, and sharing tips on ways to improve your sleep.

Detailed sleep tracking

Xiaomi claims you can get up to 15 days of battery with "typical use" from the 486mAh battery on the Watch S4. This editor is a firm believer that a watch, digital or not, needs to display the time all the time, so I used the Watch S4 with the always-on display and notifications on, a one-hour daily workout, and sleep tracking at night. The most I got was three days, but the watch nearly died. Two days were a consistent result. You can squeeze more out of the Xiaomi Watch S4 if you turn off the AOD and stick to raise to wake, more still if you don't use it for sleep tracking.

Conclusion

You can get the Xiaomi Watch S4 for below €200 - a great price. Normally it's €170 but it's often discounted by 10% or 20% - we love a deal. Smartwatches in the vicinity of the Watch S4 in terms of build quality and specs are more expensive.

That makes it simple - the Xiaomi Watch S4 is a superb timepiece with top-tier specs at a great price. We have very little to complain about, aside from the 2-pin magnetic charger.

Pros

• A pretty design, standard 22mm lug size
• The swappable bezel is a dream come true for customization
• The rotating crown is a huge upgrade
• Excellent display
• Good selection of high-quality faces with paired AOD modes
• HyperOS 2 is functional and fluid
• Affordable

Cons

• You can't customize the buttons
• Fiddly 2-pin connector
• Doesn't live up to the 15-day battery claim