Xiaomi Watch S4 smartwatch review: Affordable elegance

Xiaomi fitness trackers can be a hit-and-miss, in our experience. We were so impressed by the ultra-cheap Xiaomi Smart Band 9 that we included it in our guide to the best fitness trackers, but the more recent Xiaomi Watch 2 disappointed us with its temperamental battery life and clumsy navigation. Now, another fitness tracker from Xiaomi has landed on our wrists. So, which camp does the Xiaomi Watch S4 belong to: is it another mediocre wearable, or one of the best budget fitness trackers on the market?

At first glance, the scale appears to be tipped in its favor. The Xiaomi Watch S4 is unlike any wearable we have tested before, and that is mostly due to its unique design.

To start with, it looks surprisingly “premium” for a watch that costs just £129.99/€159.99 (while it is not available in the US just yet, we expect it to be priced at around $149.99 just like its predecessor Xiaomi Watch S3.) It is also highly customizable. The Xiaomi Watch S4 features interchangeable bezels, removable straps and a wide range of watch faces.

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Design tweaks aside, it also boasts two weeks of battery life, stacks of fitness-tracking features and plenty of mini-apps. Needless to say, we were keen to put this smartwatch through its paces.

Xiaomi Watch S4 review

Xiaomi Watch S4: Design

• Customizable bezel and straps
• Classy and comfortable to wear
• Feels sturdy and durable

The Xiaomi Watch S4 is a fashionista's dream. Although its frame is made of aluminum alloy, it is crafted so skillfully that it resembles premium stainless steel, and the watch itself is so tastefully designed that it looks more like a pricey Withings ScanWatch than a fitness tracker costing less than $150. You can also customize its design exactly how you like it.

The Xiaomi Watch S4 is available in three color options (Silver, Rainbow and Black), but thanks to its interchangeable bezels, there are plenty more styles to choose from should you wish to shake things up a bit. The straps are removable, too. Whether you want a brightly colored waterproof wristband or a stylish leather strap, the Xiaomi Watch S4 can let your personality shine through. We really liked that, and wish more brands would offer such customizability.

The Xiaomi Watch S4 not only looked good, it was also comfortable to wear. This fitness tracker weighs 1.59 oz (44.5 g) without a strap, which makes it slightly heavier than an Apple Watch, for example, but it did not weigh our wrist down. Navigating it was also a breeze. The Xiaomi Watch has a touchscreen, a rotating crown and a side button, and this combination of controls makes it easy to switch between settings on the go. Overall, no complaints.

It also seemed relatively durable. We tested the Xiaomi Watch S4 for almost two months and did not notice any scratches or wear-and-tear damage during that time. While it is admittedly not as sturdy as some of the more premium fitness trackers out there — aluminum alloy can't withstand the same harsh conditions as titanium or stainless steel, for example — it should not fall apart at the first hurdle, either.

The only gripe we had regarding the Xiaomi Watch S4 was with its default silicone strap. This is quite thick and grippy, so it tended to pinch against our skin as we tucked it under, and we sometimes struggled to tighten it up on our wrist. However, this is not really that big a deal since you can easily swap it for another strap.

Xiaomi Watch S4: Display

• Colorful 1.43-inch AMOLED display
• No Gorilla Glass or Sapphire Crystal on the screen
• Plenty of watch faces available

The Xiaomi Watch S4 features a bright, colorful 1.43-inch AMOLED display. We liked it a lot: it was easy to read and navigate, whether in direct sunlight or dimly lit environments, and did not accidentally switch itself on upon contact with water droplets. The touchscreen had a good sensitivity to touch and never lagged or froze.

One of our favorite things about the display was its exceptional customizability. Whether we wanted our Xiaomi Watch S4 to look like a classic analog watch or a futuristic device brimming with health stats, there were plenty of watch faces to suit our preferences. Plus, they were all free to download. Many smartwatch brands charge a small fee for their watch faces, so this is a big point for Xiaomi.

Xiaomi Watch S4: Features

• Plenty of health-tracking and smartwatch features
• Dual-frequency GPS, compass and barometer
• Some features require a Xiaomi phone

The Xiaomi Watch S4 offers an impressive array of features, from one-tap health insights and phone notifications to weather reports and on-wrist running courses. This fitness tracker was clearly designed to appeal to a wide range of users and circumstances. However, this universal approach is not without its flaws.

Some of the best features in the Xiaomi Watch S4 relate to health and fitness. This wearable can continuously monitor your heart rate, stress and blood oxygen, and it can tell you how well you slept, when your period is due, how hard you exercised and how much post-exercise recovery your body needs. Moreover, the Xiaomi Watch S4 can combine all of these data points into an easy-to-understand “vitality score” — a stat that indicates how balanced your physical activity is. If you work out regularly without overexerting yourself, get enough steps in and sleep well, this vitality score will go up.

All health stats can then be accessed in the free Mi Fitness app. We liked this app — it is easy on the eye and all the metrics are presented well and explained in sufficient detail without overcomplicating anything. This makes the Xiaomi Watch S4 a particularly useful tool for beginners.

However, this also means that some nuances and complex insights may be lost. For example, the sleep tracking is limited to "deep" and "light" phases, while your workout logs focus predominantly on heart rate activity and calories burned, without getting into the finer details of exercise performance. Serious exercisers and data geeks may be disappointed here. That said, the Xiaomi Watch S4 can be connected to third-party apps like Strava and Suunto, so certain more advanced metrics can be viewed there.

We also liked its extensive smartwatch capabilities. For example, the Xiaomi Watch S4 can relay phone notifications, store music, take photos remotely or locate your position using dual-frequency GPS and a compass. It also comes with fall detection, barometer, stopwatch, voice recorder, flashlight and many more features and mini-apps. However, some of these features — such as NFC payments, customizable gesture controls or smart home connectivity, for example — are only available to those who own a Xiaomi phone.

Xiaomi Watch S4: Performance

• Accurate sleep and heart rate measurements
• Battery life shorter than advertised
• Some workout-tracking features lack precision

Performance-wise, the Xiaomi Watch S4 did not disappoint us, but it did not particularly impress us either. Its workout-tracking features and battery life fell short of our expectations, but then this smartwatch redeemed itself with relatively accurate health-tracking features and flawless data transfer. Overall, the performance of the Xiaomi Watch S4 reflects its affordable price and we can't really complain about that.

Starting with the negatives, Xiaomi claims that the Watch S4 has up to 15 days of battery life, but that did not match our experience. While it may be possible for this fitness tracker to last two weeks on a single charge, we suspect this only applies if it is not used too often. We wore our testing unit nearly every day and night, continuously monitoring our vitals and tracking at least four hour-long workouts a week, and even without the Always-on screen enabled, we only managed to squeeze a maximum of 10 days out of it. That said, the Xiaomi Watch S4 still offers a better battery life than many other fitness trackers in its price range.

We were also underwhelmed by some of its workout-tracking features, particularly when it came to movement analysis. For example, the step count was reasonably accurate, but not precise enough to satisfy the needs of hiking pros, while the stroke rate (number of arm strokes per minute, a key metric in indoor rowing) differed by as much as 10%. Moreover, the “calories burned” figure always seemed too high, but then this stat is notoriously difficult to capture and each brand uses a slightly different algorithm to calculate it.

On the other hand, the Xiaomi Watch S4 seemed very accurate at measuring our sleep. It picked up all of our naps and correctly assessed when we went to bed and woke up, and its assessments of our sleep quality tended to hit the mark.

Heart rate measurements were also relatively accurate. During one workout, we wore both our Xiaomi Watch S4 and a Polar H9 chest-strap heart rate monitor, then compared the measurements given by the devices. Our testing unit did a good job of assessing heart rate during rest and low- to moderate-intensity activities, and while it did become less reliable with high-intensity exercise, it did not perform any worse than some far more premium fitness trackers.

Lastly, we liked the speedy connectivity between our watch and the Mi Fitness app. We experienced no data transfer hiccups while using the Xiaomi Watch S4, and all system updates were performed swiftly and with no interruptions.

Xiaomi Watch S4: User reviews

At the time of writing this review, the Xiaomi Watch S4 was fresh out of the factory gates, so there were not enough user testimonials to give us a clear picture. However, initial reviews on social media seemed predominantly positive.

Should you buy the Xiaomi Watch S4?

✅ Buy it if: You want a fashionable, multi-purpose smartwatch on a budget. The Xiaomi Watch S4 is classy, exceptionally customizable and packed with an array of features, and does a relatively good job of tracking your sleep and heart rate. Not to mention, it costs less than $150.

❌ Do not buy it if: You are a seasoned exerciser looking for a performance-oriented fitness tracker. While it delivers reasonably good value for beginners, the Xiaomi Watch S4 does not track complex fitness stats or provide detailed movement analysis.

If the Xiaomi Watch S4 is not for you

The Amazfit Balance is a great alternative to the Xiaomi Watch S4. While it is nowhere near as customizable or stylish, it offers similar features and good tracking performance for the same amount of money.

If you are looking for something more affordable, consider the Xiaomi Smart Band 9. This fitness band may not be as robust and classy as the Xiaomi Watch S4, but it uses the same app and has all the key features you need to kickstart your fitness routine. Plus, it is nearly $100 cheaper.

For serious athletes and outdoor enthusiasts, we would recommend the TicWatch Atlas. It is half the price of some of the more premium Garmin watches, but its durability and tracking features are nothing short of impressive.

Xiaomi Watch S4: How we tested

We spent two months testing the Xiaomi Watch S4, looking at its design, features, tracking performance, ease of use, connectivity with third-party devices and value for money. We wore it during the day, while sleeping and when doing a range of activities, from hikes in the great outdoors to gym-based weightlifting and high-intensity cardio.

Finally, we assessed the accuracy of our Xiaomi Watch S4 by comparing its heart rate measurements with the data we obtained using a more precise Polar H9 chest-strap heart rate monitor.