Xiaomi Watch S3 review

Xiaomi’s smartwatch game has been constantly evolving since the first Mi Watch hit the scene in 2019. Since then we’ve seen various Xiaomi wearables: some with simple proprietary operating systems that have changed more names than features, and others with those of Google more powerful, but power-hungry WearOS. The Xiaomi Watch S3 is the brand’s first smartwatch to launch with HyperOS, the manufacturer’s in-house operating system that powers numerous other devices, including IoT appliances and the manufacturer’s SU7 electric car.

The Watch S3 offers everything you need in a smartwatch: a bright and crisp AMOLED screen, the standard mix of health and activity tracking, GNSS positioning, NFC payments, and the ability to take calls from your wrist. It’s also highly customizable with interchangeable bezels and straps allowing you to tailor the watch to your style.

TO €150/£130 in Europe, Xiaomi is positioning the Watch S3 as its go-to smartwatch for 2024, and we’ve spent the last two weeks testing it.

Specifications of the Xiaomi Watch S3

• Screen: 1.43″ AMOLED touchscreen, 466 x 466 px resolution, 60 Hz refresh rate, 600 nit peak brightness
• Straps: Detachable straps, width 22mm, adjustable length 140-210mm
• Characteristics: 5ATM Rating, Real-time Heart Rate Monitor, 24/7 Blood Oxygen Level Monitoring, Sleep Monitoring, Stress Monitoring, Sports Monitoring, VO2 Max, Pedometer, Meditation, Notifications, Inactivity Alert, phone search, weather forecast, music and camera control, recorder, alarm clock, stopwatch, compass, barometer, flashlight
• Sports Modes: Outdoor running, indoor running, outdoor walking, outdoor cycling, hiking, strength training, skipping rope, freestyle (more than 150 in Mi Fitness app)
• Sensors: 12-channel PPG optical heart rate sensor, SpO2 sensor, 3-axis accelerometer, barometer, rotor vibration motor
• Connectivity: Bluetooth 5.2, compatible with Android 8.0 and iOS 12+, dual-band L1+L5 GNSS, NFC (depending on market), microphone and speakers
• Drums: 486 mAh
• Colors: Black silver
• Dimensions: 47×47×12mm
• Weight: 44 grams without strap

Project

The Watch S3 brings a familiar design in line with the Xiaomi Watch 2 generation. It’s a large watch with a 47mm case and a 1.43-inch AMOLED screen that definitely takes some getting used to if you’re new to from a smaller watch or smartband. The big news on the Wach S3 is the stainless steel bezel which is detachable and allows for unprecedented customization options.

A quick counterclockwise rotation detaches the bezel and frees the watch to accommodate any of four additional styles which we assume will only increase in number from here. The bayonet mount, similar to what you might find on a camera lens, is a really neat design choice that locks in securely. Each watch bezel features its own dial that activates immediately when attached.

The interchangeable bezels paired with the endless choice of 22mm watch bands allow for unprecedented customization, which is a great way to breathe new life into your watch across the board. Unfortunately, the bezel is only cosmetic and doesn’t add any functionality like you’d have on a Galaxy Watch6 Classic and its rotating bezel. Our silver-colored Watch S3 review unit comes bundled with a matching stainless steel watch bezel and a silver-colored fluorinated rubber watch strap.

The Watch S3 feels just as premium as more expensive smartwatches we’ve tested with its sleek aluminum frame, stainless steel watch bezels, and wide range of 22mm watch band options. Despite the large trainer, it feels somehow light and unobtrusive on the wrist. The S3 watch weighs 44 grams without the strap and is 12 mm thick. It’s also waterproof to 5ATM, so swimming sessions are a breeze.

The 1.43-inch AMOLED display offers saturated colors and excellent viewing angles. It gets bright enough for outdoors too, reaching a maximum of 600 nits of peak brightness, and it also has a dedicated auto-brightness sensor. The display refreshes at 60Hz making it snappy and is also protected by Gorilla Glass 3. We should note that some of the AOD options are harder to see in direct sunlight.

There are two buttons for navigation: the top one acts as a shortcut to the app menu and also acts as a back button while the bottom one is programmable and can be paired to launch any app but acts as a shortcut to the workout page by default .

Despite the aluminum alloy frame and stainless steel bezel, Xiaomi Watch S3 weighs 44 grams, does not feel heavy on the wrist and is comfortable to wear all day. The retail package features the S3 Watch, its proprietary two-pin magnetic charging puck terminating in a USB-A cable, and the usual mix of manuals. Wireless charging appears to be the only omission.

Characteristics

Xiaomi Watch S3 packs a long technical sheet and one of its main features is HyperOS. Xiaomi’s proprietary IoT platform looks familiar to MIUI Watch, but unfortunately it doesn’t support third-party apps outside of China.

There are 31 built-in apps including Amazon Alexa, a phone dialer, a voice recorder, an NFC card app along with all the usual set of apps you’d find on a smartwatch such as an alarm, a pretty detailed weather app and also health and activity tracking app. You also get reminders, a calendar, contacts, media controls, breathing exercises, a barometer, a compass, a flashlight, and a camera shutter.

Xiaomi Watch S3 App

The Watch S3 comes with a microphone and speaker that lets you make and receive calls from your paired phone via Bluetooth. Our review unit lacks eSIM connectivity unlike the Chinese versions, achieving total phone independence. Xiaomi also offers push notifications on the watch for most apps, but these are usually just simple alerts without the ability to respond or trigger additional actions.

There are two vibration settings with standard and strong values. In addition to the two physical buttons, Xiaomi has added quick gestures which are a gimmicky way to launch additional apps by tilting your wrist 90 degrees or making a circular motion. Options are limited here with support for activating Amazon Alexa, the weather app, rejecting incoming calls, and activating the remote camera shutter feature on the paired phone.

The Watch S3 also supports dual-band (L1 and L5) satellite positioning over BeiDou, GPS, GLONASS, Galileo and QZSS, as well as NFC payments via Xiaomi Pay. The caveat with payments is that you can only add cards issued by Mastercard and pay at Mastercard payment terminals.

As for health monitoring, the Watch S3 features a 12-channel heart rate sensor with 24/7 heart rate monitoring, SpO2 monitoring, stress, and sleep monitoring with a new sleep algorithm updated offering REM sleep and breathing scores.

Xiaomi’s Mi Fitness app is a mandatory installation that you’ll need on your paired phone to activate most features on the Watch S3. The watch supports a total of 161 workout modes that cover almost every activity you could think of, from running to weightlifting to nuances like kite flying and board games.

You can access the full list of activities within the Workouts app on the watch, which is neat, and Mi Fitness can keep up to a month of health and training data. You can also sync your health and activity data with Apple Health, Google Fit, Strava and Suunto.

There are 13 pre-loaded watch faces with different levels of customizable elements for watch complications and accent colors. You’ll also find a wide selection of additional watch faces in the Mi Fitness app.

The Watch S3 also comes with fall detection and emergency assistance features, although they’re limited to Android users. These include the ability to call emergency services or an emergency contact of your choice and send an SMS message if you fall. You can also store your key medical data on the watch which will be displayed when you activate the emergency assistance function. Please note that these settings need to be configured in advance in the Mi Fitness app on your phone.

Software and performance

Although its name is new, HyperOS offered no tangible difference compared to previous non-Wear OS Xiaomi watches during our testing. The app icons and menus have received a fresh coat of paint, but that’s about it. Xiaomi says HyperOS will allow for smoother connectivity and integration between its devices across the board, but for now it’s mostly the same thing with a new name.

While Google’s WearOS offers broad third-party app support and more savvy smartphone replacement capabilities, a watch like the S3 with HyperOS is preferable if you just want to cover the basics of a smartwatch and still get durability of the exceptional battery. Aside from a dedicated maps app and the ability to respond to notifications, I didn’t miss any features on the Watch S3 during my review period.

The user interface is simple and works without any noticeable lag. You can interact with the watch in several ways: by double-tapping the screen, raising your wrist, or pressing one of the side buttons. From there you can swipe down to view notifications or swipe up from the bottom to toggle the control center page.

By swiping left or right you can access your widgets which are app tabs grouped together. You can set up up to four apps in a single widget tab directly from the watch or in the widget tab on the Mi Fitness app. Notifications on the Watch S3 arrive promptly but we’ve already covered the lack of additional features as you can just ignore them.

The built-in speaker does the job but is a little difficult to hear during calls in noisier environments. The microphone handles voice reception well, and people on the other end of the call report strong, clear reception from me. The Watch maintained a stable connection with my paired iPhone 15 Pro throughout the review period with no dips

Health monitoring

The Watch S3 supports configurable heart rate monitoring via a 12-channel PPG optical heart rate sensor. You can configure readings between 1 and 30 minute intervals with the shorter values ​​using up more battery life. Heart rate readings were on par with other smartwatches recently tested. You can also set high and low heart rate alerts with alerts appearing when you’ve gone above or below a predetermined threshold.

Blood oxygen (SpO2) monitoring with 24/7 readings is also supported. In terms of accuracy, we found that both heart rate and SpO2 results offer similar values ​​to what you would get on competing smartwatches and other health trackers such as dedicated pulse oximeters. Don’t expect medical grade readings here as wearable devices like this are meant to monitor your overall well-being. We compared the watch’s heart rate and blood oxygen measurements to those of a specialized heart rate monitor and pulse oximeter and got similar values.

Heart rate, blood oxygen and sleep readings in the Mi Fitness app

Xiaomi is touting its new sleep analysis algorithm with claims of greater accuracy, and we can confirm that it does a great job of recording accurate bedtime and wake-up times. Get a detailed breakdown of your sleep by category with REM (deep, light, rapid eye movement) sleep. Wearing the Watch S3 for a week will generate your own personal sleep information report with an assigned sleeping animal based on your sleep pattern, as well as a recommended schedule for how to set up your day for optimal rest and recovery.

I ran into a bug with some random additional wake times added to some sleep sessions even though I was in bed and not getting up at all during those nights. Hopefully, Xiaomi can fix this issue with future software updates. With the SpO2 monitoring feature enabled during sleep tracking you also get breathing scores that can alert you to early signs of sleep apnea.

Activity monitoring

Moving on to activity tracking, the Xiaomi Watch S3 did not disappoint with accurate step counting and easy-to-read essential workout data. Most training modes show your basic vitals such as graphs of heart rate, calories burned, exercise intensity, VO₂ max and suggested recovery times. Walking, running, and hiking also get more in-depth metrics like average speed, cadences, pace, and elevation gain. The watch also supports automatic workout detection for some activities including walking, running, cycling, rowing, jumping rope and elliptical.

Activity tracking metrics in the Mi Fitness app

I encountered a bug where workout tracking would randomly stop after unlocking the watch to check workout metrics. I found myself missing more than 20 minutes during a workout before noticing that the workout had been paused without any additional input from me.

GNSS positioning locks instantly when you select one of the supported workouts even if you’re indoors, which was an amazing feat. The positioning data was fairly accurate on a hiking trail, but not so much during city walks as it failed to identify the correct side of the sidewalk relative to my path.

The dedicated ski mode is a great addition that covers distance travelled, average speed, and a dedicated ski trail map that you can share with friends. Unfortunately, the Watch S3 does not support the ability to upload maps in GPX format to the watch for hiking or running, which you can do on competitors such as the Huawei GT4 and Amazfit GTR 4.

Battery life

The Xiaomi Watch S3 comes with a 486mAh battery that is said to last up to 15 days on a charge with normal usage and 5 days with Always-On Display enabled. The Watch S3 provided a decent 4.5 days of battery life in my use case. We got these numbers with the AOD turned on, all health monitoring features turned on 24/7, a few short phone calls, and a 1:30 hour daily workout. More moderate health monitoring and disabling AOD extend resistance to 7 days.

The watch is smart enough to give you an estimated battery life based on your usage pattern in the battery menu, though we found it overestimates the values. There is a power saving mode that will require a few more days of use, but you will have to turn off almost all of the watch’s features to achieve these values.

Charging occurs exclusively via the two-pin magnetic disk supplied with the watch. It’s backwards compatible with the one found on the Xiaomi Watch 2 and Watch S1 series, which is a good thing. A 5 minute charge takes the watch from 0 to 20% while a full charge takes 1 hour. The only major issue, however, is the lack of wireless charging, which is a big caveat for a smartwatch.

Verdict

Xiaomi Watch S3 offers a mix of premium construction and modular design with unprecedented customization options. The removable bezels give the watch a sense of individuality setting it apart from the competition. You can easily breathe new life into the Watch S3 with one of the colored bezels, and the standard 22mm bands provide even more customization options.

The style-focused approach is supported by accurate health and activity tracking, and while it may not offer the features of a true WearOS watch and all that entails, it does the basics well enough while offering solid durability of the battery.

The 1.43-inch AMOLED display is sharp and easy to read even outdoors in direct sunlight. The dual-band GNSS positioning connects quickly and offers reliable tracking, and Bluetooth calls work great too. Xiaomi Pay is somewhat limited by its short list of supported bank cards, and sleep tracking leaves a little to be desired.

We would also have liked to see wireless charging for those times when you don’t have the proprietary Xiaomi charger with you, and richer notification support with options to reply to incoming messages.

Ultimately, if you want to express your own style and have the ability to completely transform the look of your watch, then the Watch S3 is a great option with no real competition. It’s also included in Xiaomi 14 series pre-orders in some markets, which is a great freebie to pair with your brand new phone.