At a glance
Expert’s Rating
Pros
- Rotating crown is a good addition
- Software has more mature look
- Still delivers good battery life
- Interchangeable bezels
Cons
- Smart home controller needs Xiaomi smartphone
- Some features missing for iOS users
- New gesture controls for Xiaomi devices only
Our Verdict
The Xiaomi Watch S4 remains a good-value smartwatch that offers an improved look and a good all-round experience for the price.
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The Xiaomi Watch S4 sees Xiaomi update the cheapest of its trio of smartwatches where its party piece once again is the ability to remove the bezel to change its look.
Along with refining the way that bezel-switching works, Xiaomi is also adding in the latest version of its HyperOS operating system that brings a new user interface look, gesture features and also wants to make it easier to take control of Xiaomi’s smart home devices.
Like the Xiaomi Watch S3, the Watch S4 price remains very reasonable at just £129.99, making it an option for both Android and iPhone users that don’t want to spend big on an Apple Watch, Samsung Galaxy Watch or Google Pixel Watch.
It won’t give you all of the features those smartwatches will, but it’s about doing what it can do well and it does certainly do that in most departments.
The Watch S4 was announced at MWC alongside plenty of other new Xiaomi devices.
Design & Build
- Removable bezel design has been upgraded
- Comes in black or silver case colours
- Waterproof up to 50 metres
The best way to describe the change in look on the Watch S4 from the S3 is that things just feel a bit more refined as Xiaomi takes that bezel-heavy design and aims to elevate it.
Mike Sawh
It’s not just about the bezel either. It ditches the top physical button for a rotating crown one with the bottom button remaining now assigned to give you a shortcut to the quick settings menu.
The aluminium alloy case comes in black or silver finishes and measures only slightly larger at 47.3mm (up from 47mm) and remains the same thickness at 12mm. While the stature of the S4 feels similar to the S3, its overall look doesn’t.
We’ve been here before where smartwatch makers want to create the illusion that you’re wearing a classic timepiece and it reminds me of Samsung’s effort with the Watch Classic on that front. It doesn’t look as cheap as the price suggests it will be.
Mike Sawh
Those bezels now feel higher quality, with eight looks to pick from. That also includes straps that are woven, made from flurorubber or leather. I had an additional carbon bezel and flurorubber strap with a stitching effect designed to make it feel more premium than it actually is.
The bezel looked a lot nicer than the strap. The straps, like the bezels, are easy to clip away from the watch case and as a package, remains waterproof up to 5ATM making them suitable for a swim up to 50 metres depth.
Screen & Audio
- Features brighter 1.43-inch AMOLED display
- Can make Bluetooth calls
- No LTE connectivity
Xiaomi sticks to the same size and resolution AMOLED screen used on the Watch S3. That’s a 1.43-inch, 466 x 466 resolution one that does support an always-on display mode. The change here is now how bright that display can go now.
It promises a peak global brightness of 1,500 nits and peak brightness of 2,200 nits. To put that into perspective, a similar-sized Apple Watch promises up to 2,000 nits. Given the Watch S3 managed up to 600 nits, that’s quite a step up.
I can’t say I had massive struggles seeing the S3’s screen outside, but having a display that’s capable of going brighter can only be a good thing.
Mike Sawh
Brightness aside, it’s much of the same with the screen. It’s a very good AMOLED panel, just not the best you’ll find on a smartwatch. If displays on the Apple Watch and smartwatches like the Samsung Galaxy Watch and the Google Pixel Watch are the pinnacle, this one sits below those.
It’s vibrant and offers accurate colours and while there’s some black bezel around the screen to contend with, it’s slim enough not to feel like it’s eating into the available screen estate.
While Xiaomi has rolled out an LTE version of the Watch S4 in China, we’re not getting the same on the global version. So if you want to use it to handle calls, that’s done over Bluetooth.
The call quality is aided by dual microphones to reduce exterior noise and wind, meaning it’s suitable for chatting on your watch instead of your phone with enough clarity and overall loudness.
Software & Features
- Runs on Xiaomi’s HyperOS 2
- Stronger integration with Xiaomi smart home devices
- Promised improved third party app support
Xiaomi is sticking to its own in-house smartwatch operating system for the Watch S4, moving from HyperOS to HyperOS 2. That remains an OS that does work with Android phones and iPhones.
Like the S3, there’s going to be some features restrictions depending on the phone you’re using. Most notably iPhone users miss out on access to the onboard music player.
Mike Sawh
Among the changes, Xiaomi has tweaked the user interface, brought the rotating crown into play to good effect to make scrolling through menu screens and longer notifications a lot nicer to do.
I’d describe the user interface as feeling a bit more grown up than it was on the S3. From watch faces to widgets and how notifications are treated, it feels like a better match for its more elegant watch case exterior.
Mike Sawh
Along with doing things like making calls over Bluetooth, playing music (if you’re an Android user), remotely taking smartphone pictures or checking on your calendar a lot of the more noteworthy new features rely on you owning a Xiaomi smartphone, tablet and even Xiaomi smart home devices.
These include new gesture features to interact with Xiaomi’s tablets or controlling smart home kit from your watch.
It does also of course miss out on the third party app support and suite of Google apps you will have access to on the WearOS-powered Watch 2 Pro and Watch 2. What is present works well enough to make sure it does perform solidly as a smartwatch.
Fitness & Tracking
- Over 150 sports modes
- Dual-frequency GNSS
- Promised improved heart rate monitoring
If you want a smartwatch that can track your workouts, daily steps or just your general wellbeing, the S4 is pretty well stocked on that front.
Mike Sawh
It doesn’t have any regulatory approved health monitoring features, though it does promise to conduct a 60-second reading to check heart rate, blood oxygen levels, stress and sleep data. Xiaomi says it’s upgraded the algorithms used to crunch heart rate data to boost heart rate monitoring accuracy to 98%.
On the sports tracking front, there’s over 150 sports modes to pick from, with profiles for swimming, hiking and winter sports like snowboarding. There’s dedicated training sessions for running beginners and additional running insights into your training load, VO2 Max and fatigue levels. It’s nice to see that there’s dual-frequency GNSS support to promise improved outdoor tracking accuracy when taking your exercise outdoors.
As a fitness tracker, you’ve got a very glanceable widget on the watch to keep an eye on your progress with some watch faces able to display some of your fitness tracking stats. Daily step counts were nicely in line with two other fitness trackers I wore at the same time.
If you’re keeping an eye on your heart rate during the day, resting heart rate data captured for the day looks okay. Glancing down at readings in real-time, and the readings generally were noticeably higher. I put some of that down to a strap that didn’t always feel like it was getting that sensor close enough to my wrist, but this is something I’ve seen before.
Mike Sawh
When taking it to bed, you’ll get a nice breakdown on the watch of sleep data like stages, time slept and sleep heart rate if you’ve enabled the more advanced sleep monitoring support. The sleep tracking compared to the Oura Ring 4 generally matched up for time slept, sleep scores, with deep and light sleep stage capturing slightly more generous time spent in those sleep stages. Average heart rate was on the high side on most nights as well.
Turning it for sports tracking and it’s good to see that there’s more than a few modes that offer activity-specific metrics, with many still keeping that tracking to capturing workout duration and heart rate.
The dual-frequency GNSS support did come up slightly short with tracking distance compared to a dual frequency-packing Garmin watch, with metrics like average pace data not far off. Things didn’t massively improve on the heart rate tracking front where average readings were similar, but maximum heart readings were almost 10 bpm higher.
Mike Sawh
There are some additional features here like the ability to track stress, follow breathing exercises and track Vitality scores, but as I said, particularly about the latter, it never truly feels part of daily tracking proceedings.
Your data lives primarily inside of the Mi Fitness companion app, where I still think it could display data in a way that doesn’t feel like it’s just been dropped on the page. You do additionally have the option to share data with Strava, Suunto and Google and Apple Health if spending time in that app isn’t to your liking.
Battery Life & Charging
- Up to 15 days battery life
- Quick charge mode gives you 2-day battery
- Up to 5 days battery life
The battery numbers quoted for the Watch S4 are exactly the same as the Watch S3 and that means this is a smartwatch that’s capable of lasting weeks and less if you keep the screen on at all times. Even if you do want the screen on continuously, Xiaomi will let you keep the screen on when you’re likely to want it on and turn it off for times when you’ve got the watch off or you’re in bed sleeping.
I found using it with the always-on display on lighter usage days battery drop was around 20%. Add in use of more demanding features like GPS and continuous blood oxygen monitoring and that’s likely to be closer to 2-3 days.
So, no improvement on the S3 with that new version of HyperOS in place but at least it’s not got worse either.
Price & Availability
The Watch S4 price officially goes on sale at the same price as its predecessor, sticking at £129.99 to make it a very affordable smartwatch once again.
The Watch S3 now sits at £99.99, so it’s likely you’ll see a Watch S4 price drop at some point as well. You’ll be able to grab it from the Xiaomi website and listings have already popped up on Amazon as well.
That price puts it up against smartwatches like the Huawei Watch Fit 3 (From £119.99), Honor Watch 5 (£129.99) and means it’s considerably more bank balance-friendly than the cheapest available Apple Watch, with the Watch SE (2nd generation) sitting at £219.
It’s the same story when compared to the cheapest Samsung smartwatch, which is the Samsung Galaxy Watch FE (from £214).
Check out our list of the best budget smartwatches.
Should you buy the Xiaomi Watch S4?
I think if you liked the Xiaomi Watch S3 and like the idea of an upgrade that mainly makes its standout feature a much nicer one, then that would be the biggest reason to upgrade. HyperOS 2 feels more grown up than the last version, while a lot of the software changes are really connected to you having a Xiaomi phone or smart home device.
If you’re looking for one of the best smartwatches under £150, this is still one of the best you can get. It’s not going to give you that richer app ecosystem that Apple or Wear OS watches will get you, but there’s enough to like here.
Amazfit is a problem for Xiaomi with the Active 2 (both premium and non-premium) offering a rich set of features for less. It doesn’t have that more customizable design and that’s something Xiaomi has in its favour for the Watch S4 at least for now.
Specs
- 1.43-inch, AMOLED always-on display
- 5 ATM water resistance rating
- Heart rate sensor with blood oxygen sensor
- Dual-frequency GNSS
- Up to 15 days battery life
- Bluetooth 5.3
- Up to 15 days battery life
