Xiaomi Watch S4 review: A bright screen and a bezel that keeps things fresh
Xiaomi Watch S4
Pros
- Bright 1500-nit AMOLED display for excellent outdoor visibility
- Interchangeable bezel for easy customization
- Rotating crown improves navigation
- Accurate GPS and heart rate tracking during runs
- Long battery life (up to 15 days with typical use)
Cons
- No major new health sensors compared to the S3
- Does not connect to external heart rate chest straps
Xiaomi Watch S4: One minute review
The Xiaomi Watch S4 builds on the S3’s solid foundation, refining the experience in small but meaningful ways. The brighter 1500-nit AMOLED display is a big plus, making outdoor visibility better. The interchangeable bezel keeps the design flexible, and the rotating crown makes scrolling through menus feel smoother. Overall, everything feels a touch more premium.
For fitness tracking, the S4 performs well. GPS is highly accurate, and heart rate tracking is reliable for most runners, though it can be less precise during high-intensity workouts. Battery life remains a strong point, lasting up to 15 days with regular use. Plus, a quick 5-minute charge can give you enough power for another two days, making it easy to keep the watch going without long charging times.
The smartwatch features still feel a bit limited. There are plenty of watch faces to choose from (over 200), but the app selection is small, and third-party support isn’t as robust as on Wear OS or Apple Watch. If app variety is a priority, this might not be the best option.
But for anyone looking for a stylish, customizable smartwatch with solid fitness tracking, long battery life, and a refined user experience, the Xiaomi Watch S4 is an easy recommendation. It’s not a game-changer, but it improves on the S3 in all the right ways.
The Xiaomi Watch S4 can be purchased from Xiaomi’s official store.*
Xiaomi Watch S4 review: Design, hardware
Look & feel
I reviewed the Xiaomi Watch S3 last year, and while the S4 sticks to a very similar design, it feels more refined in almost every way. The aluminium alloy frame and stainless steel bezel are still here, now with a high-gloss PVD finish that gives it a more polished look. Weighing just 44.5 grams, the device remains comfortable enough for all-day wear. I tested the black version, but there’s also a white model for those who prefer a brighter style.
The interchangeable bezel is, once again, one of the standout design features. Swapping it out is as simple as twisting it off and clicking in a new one. Combine it with a different strap and watch face, and the S4 can take on a completely new look in seconds. Xiaomi has also improved the bezel structure for a more secure fit and added a drop reminder—if the bezel comes loose, you’ll get a vibration and a notification. Having misplaced the bezel on my S3 a few times, this small but practical upgrade is definitely appreciated.
The display is where you notice another upgrade. It’s the same 1.43-inch AMOLED with a sharp 466 x 466 resolution, but now it reaches 1500 nits of brightness with a peak of 2200 nits. That’s a big jump from the S3, and surpasses the Apple Watch Series 10 (2,000 nits). Even in direct sunlight, the screen stays clear, and the auto-brightness does a good job of adjusting on the fly.
The size of the watch has increased slightly, but it still sits comfortably on the wrist with its slim 12mm profile. At 47mm, it’s definitely on the larger side, so it might not be ideal for smaller wrists. Water resistance remains at 5ATM, so you can take it swimming or wear it in the rain without worrying about damage.
One change that stands out is the switch from two flat buttons to a fully functional rotating crown with a single button. The crown makes scrolling through menus feel much smoother, and the button is programmable, so you can set it to launch workouts or other shortcuts. Navigation is a bit different than previously —swipe up or down to switch widgets, swipe down from the home page for notifications, and swipe left from the home page to switch watch-faces. Simple once you learn the new order of things.
Overall, the Xiaomi Watch S4 takes what worked with the S3 and improves it in small but meaningful ways. The screen is brighter, the materials feel nicer, and the rotating crown makes things easier to navigate. It still offers the same customization options, but with a bit more polish and a slightly more premium feel.
Under the hood
Under the hood, the device packs a solid set of sensors, including a 12-channel optical heart rate sensor with 24/7 blood oxygen monitoring, an accelerometer, gyroscope, geomagnetic sensor, and barometric pressure sensor. All of this is unchanged from last year, although it’s likely the company has upgraded some of these sensors with new versions. The built-in microphone and speakers are back as well, making it easy to take calls or use voice controls.
Connectivity gets a slight boost with Bluetooth 5.3 instead of 5.2, along with Wi-Fi for a stable connection to your phone or compatible networks. Location tracking is handled by dual-band GNSS (BeiDou, GPS, GLONASS, Galileo, QZSS), ensuring accurate outdoor workout tracking. More about that later.
Battery Life
The Xiaomi Watch S4 runs on HyperOS 2.0, an updated version of Xiaomi’s smartwatch operating system. Like its predecessor, the software is lightweight and efficient, helping to maximize battery life without unnecessary drain.
Powering the watch is the same 486mAh lithium-ion polymer battery, charged via a 2-pin magnetic dock with a USB-A cable. Xiaomi’s official numbers remain unchanged—up to 15 days on a charge with typical Android use and 14.5 days with iOS. If you keep the Always-On Display (AOD) enabled, battery life drops to around 5 days.
From my experience, these estimates are pretty accurate. As long as you don’t rely heavily on AOD, charging won’t be a frequent concern, making the Watch S4 just as reliable as before when it comes to longevity. Also a quick 5-minute charge is enough to power the watch for up to 2 days, which is quite a feat.
Xiaomi Watch S4 vs S3: Tech specs comparison
The Xiaomi Watch S4 isn’t a massive upgrade over the S3, but it does have some nice tweaks. An important one is the screen—it now hits 1500 nits of brightness, way better than the 600 nits on the S3, so it’s much easier to see in sunlight. They also ditched the two flat buttons for a rotating crown and a single flat button, which should make scrolling smoother. It’s a tiny bit bigger and heavier, but you wouldn’t really notice. Another small change is Bluetooth 5.3 instead of 5.2.
Most of the other stuff is the same—same battery, water resistance, and GPS tracking. Both watches run Xiaomi HyperOS, though the S4 has version 2.0, which might have a few extra tweaks. If you already have the S3, it’s probably not worth upgrading unless you really want that brighter screen, the crown, or cellular connectivity.
Feature | Xiaomi Watch S4 | Xiaomi Watch S3 |
|---|---|---|
Number of physical buttons | Flat button and rotating crown | 2 flat buttons |
Size | 47.3 x 47.3 x 12mm | 47.0 x 47.0 x 12.0 mm |
Display | 1.43 inch AMOLED (466 x 466 pixels, up to 1500 nits) | 1.43 inch AMOLED (466 x 466 pixels, up to 600 nits) |
Weight (without strap) | 44.5 grams | 44 grams |
Connection | Bluetooth 5.3, Wi-Fi 802.11 b/g/n | Bluetooth 5.2, Wi-Fi 802.11 b/g/n |
Typical RRP | $185 | $150 |
Xiaomi Watch S4 review: Health & fitness tracking
The Xiaomi Watch S4 continues to strike a balance between smartwatch and fitness tracker, offering solid health monitoring without going too deep into pro-level sports metrics. It covers all the essentials and adds a few refinements over its predecessor.
As always, it’s worth spending some time in the settings when you first start fiddling with the watch. There are a few options to tweak, like adjusting the frequency of heart rate readings. The higher the frequency, the faster the battery drains, so you can choose what works best for you. You can also enable alerts for high and low heart rates, keeping an extra layer of awareness on your health.
Step counting, sleep tracking, resting heart rate measurements, and blood oxygen readings remain accurate and consistent. Xiaomi says its heart rate tracking now reaches 98% accuracy, thanks to an improved algorithm. The one-tap health insights feature is a nice feature, giving a quick snapshot of key health metrics in just 60 seconds.
The Mi Fitness app remains the hub for all your data. It’s functional and easy to navigate, though it still lacks some of the polish seen in competing apps. But it is getting better. Worth a mention is that it now supports Health Connect and workout apps such as Strava and Suunto.
Sleep tracking continues to be a strong point, even more so with the S4. You can spend a lot of data sifting through the detailed sleep insights. There’s a sleep score, and Xiaomi’s “Sleep Animal” feature, which assigns you a character based on your sleep patterns—similar to what Fitbit and Google offer.
A new addition that I like is the Schedule Recommendation section. It looks at your sleep history and other data to suggest how you should structure your day and when to go to sleep in the evening.
Xiaomi hasn’t introduced any major new sensors this time around, so features like skin temperature tracking or HRV monitoring are still missing. Which is a bit disappointing. But what is included works well. Stress tracking is also improved, with new guided breathing exercises designed to help with focus, anxiety relief, and sleep.
Safety features are back, including fall detection and emergency assistance (for Android users). If you take a hard fall, the watch can contact emergency services or a chosen contact, send an SMS, and display medical information. It’s something you hope never to need, but it’s good to have just in case. To activate emergency SOS, click the side button of the device three times in a row.
If you choose to do so, you can also enable a PIN for your watch. This locks your wearable when you are not wearing it.
Xiaomi Watch S4 review: Sports tracking
The Xiaomi Watch S4 supports tracking for over 150 sports, with automatic detection for some of the most common ones. As a runner, this was one of the features I was most eager to test.
The watch didn’t disappoint. I wore it on multiple runs alongside the Garmin Forerunner 955 for comparison. GPS accuracy was solid and quick to connect, with one exception where it took a few minutes to lock onto a signal. That seemed to be an outlier, though—most of the time, it locked in within seconds.
Heart rate tracking was reliable for easy and mid-effort runs, matching up well against the Garmin. However, at very high intensity, accuracy started to slip. I suspect this is due to the size of the watch. I have slender wrists, and the S4 is quite large, so getting a perfectly snug fit during intense movements can be tricky.
Looking at the numbers, on a recent steady 7.5K run, the Xiaomi estimated my average heart rate at 134bpm with a max of 161bpm. The Garmin recorded 134bpm and 157bpm, which is very close. GPS distance tracking was also excellent, coming within 10 meters of the Garmin for that run—an impressive result.
For a high-intensity 5K, the difference was more noticeable. The Xiaomi estimated my average heart rate at 159bpm and max at 181bpm, while the Garmin recorded 151bpm and 167bpm. That’s a bigger gap, but it’s a common issue with wrist-based heart rate tracking during intense activity. Unfortunately, the Watch S4 doesn’t support external heart rate chest straps, which would have helped in this scenario. That said, for those with larger wrists who can get a tighter fit, this may not be as much of a problem.
Beyond that you get some nice run tracking data. In addition to all of the usuals, the Xiaomi spits out a bunch of running dynamics metrics. This includes Ground Contact Time, Vertical Amplitude and Vertical Ratio. Plus you get Training Effect Training Load and Vo2Max – all of which seem reasonably accurate.
Xiaomi Watch S4 review: Smartwatch features
The Xiaomi Watch S4 isn’t just about fitness—it’s got plenty of smart features to keep things convenient. You’ll get notifications for calls, texts, social media updates, and calendar reminders right on your wrist. You can set up quick responses to reply to messages. The built-in microphone and speaker are back, making it easy to answer calls directly from the watch and there’s NFC for contactless payments.
The app selection is still pretty limited compared to something like a Wear OS or Apple Watch. You get around 30 built-in apps, plus a few third-party options—but, like before, most of those are only available in China. Wrist gestures are also here again, letting you flick your wrist to reject calls or open apps. It’s a cool little trick, but probably not something you’ll use all the time.
Customization is a strong point, with over 200 watch faces to choose from. And some of these look stunning on the high-res display. There’s everything from animated pets and portrait-style faces to functional dials like Clearheaded (which tracks stress with emoji reactions), Wild Walker (which shows direction and altitude), and Time Zone (which tracks multiple time zones with a GMT dial). Whether you want a simple, sleek look or a data-packed home screen, there’s plenty to play around with.
Music controls work just like before—you can play, pause, and skip tracks when your phone is connected. But if you want to go fully phone-free, you can transfer MP3 files straight to the watch’s 2.2GB of storage through the Mi Fitness app. Perfect for runs or workouts when you don’t want to carry your phone around.
The Xiaomi Watch S4 can be purchased from Xiaomi’s official store.*
*We are a review site that receives a small commission from sales of certain items, but the price is the same for you. Purchasing items by clicking on links in this article allows us to run this website. We are independently owned and all opinions expressed here are our own. See our affiliate disclosure page for more details.
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