Galaxy Watch 4 review: Still the best Android smartwatches around

Body composition scans and snore detection are interesting, but it’s Samsung’s core watch experience that delivers.

David Imel for Engadget

When Google and Samsung announced they had teamed up on the latest version of Wear OS, many hoped it would finally bring a smartwatch for Android users that would rival the Apple Watch. With the relatively robust third-party app library from Google and Samsung’s intuitive interface, the platform was promising. The Galaxy Watch 4 and Watch 4 Classic are the first devices running the new “Wear OS powered by Samsung.”

But software isn't their only intriguing new feature. Samsung also upgraded the biometric sensors to offer, among other things, a body composition scanner and improved sleep tracking. Throw in new 5nm processors and sharper screens and the Watch 4 series looks like a meaty update. Has the Apple Watch finally met its match? Probably not, but one can hope.

Before we get too far ahead, it’s worth noting that other than the Classic having a physical spinning bezel and a stainless steel case, there aren’t major differences between the two Watch 4 models. They have the same upgraded sensors, battery and screen sizes, so most of what I’m going to cover in this review applies to both models, unless I specify otherwise.

Side view of a black Samsung Galaxy Watch 4 on a person who has their arms folded across their chest.
David Imel for Engadget

Wear OS and One UI

Let’s start with the most intriguing change in both watches: Wear OS. Honestly, if I didn't know the Watch 4 was using a whole new OS, I might have just assumed this was a minor Tizen update. You’ll still swipe sideways or spin the physical bezel on the Classic to scroll through all your widgets and use the touch-sensitive ring around the regular Watch 4’s screen. But instead of All Apps being one of the pages on the right, they’re now below the home screen. There’s also a customizable quick settings panel above the main page, too.

Of course, the dead giveaway that there’s something more going on here is that you can now download apps from the Play Store directly from your wrist. A section in the Play Store shows all the apps on your phone that have Wear counterparts and I easily added Telegram and Spotify from this page. This seamless installation of apps that are already on your phone onto your watch is one of the features that Samsung said its One UI software would enable. I was expecting them to automatically show up on the watch without me doing any work, but I guess this way you get to decide what you want on your wrist.

One UI also allows for settings on your watch and phone to sync, so that when you enable Do Not Disturb on one, the other activates it too. When you play a song on your phone, a media controller is supposed to appear on the wearable. These only work with Samsung’s phones, though, so if you’re using some other Android device this doesn’t apply. Oh and while we’re at it, the Watch 4 series doesn’t work with iOS, unlike its predecessors. But if you’re an iPhone owner you probably weren’t considering an Android watch to begin with.

Close up of a black Samsung Galaxy Watch 4 Classic with two fingers on the physical rotating bezel.
David Imel for Engadget

One last thing that Samsung added via One UI: gesture controls. In theory, this will let you answer or dismiss calls by flicking your wrist or lifting your arm. I enabled the setting and was able to answer a call by raising my wrist as instructed, but dismissing them by rotating my fist did not work. This could potentially make it easier to use the watch with one-hand or when I have my arms full, but they don’t work very well at the moment and are limited to responding to calls or messages.

New sensor and new features

In addition to brand new (yet familiar) software, the Watch 4 line also got a serious hardware upgrade. Samsung used a new 3-in-1 biometric sensor that not only should allow for faster and more consistent readings, it also enables bioelectrical impedance analysis (BIA) to offer body mass scans.

The Watch will first ask for basic information like your gender, age and weight. Then, it tells you to place your middle and ring fingers on the two buttons on the edge. It’ll also instruct you to stay still and lift your arms away from your body while it scans, which takes about 15 seconds. Once it’s done, the system spits out a comprehensive breakdown of your body, saying how many pounds of water, fat and skeletal mass it detected.

Taking a body composition reading on the Samsung Galaxy Watch 4
David Imel for Engadget

I’ve been excited about this new feature, since body composition is generally a better way to understand your overall health than BMI. I’d been using Amazon’s camera-based system in its Halo app to determine my body fat percentage and though that’s been a handy and seemingly accurate method, BIA is a more conventional and common means.

The problem I realized after a few days is that a watch might not be the best place to have BIA sensors. Since the scan requires you to be fairly still and not touch other parts of your body, it can be quite awkward to do. That would be fine if the only issue were standing in an uncomfortable stance for 15 seconds every now and then, but small changes in your posture can affect your result.

I took two scans just seconds apart, one with my arms lifted further away from my body than the other. The first time, I got a 26 percent fat scan result, and the next I got 30 percent. I wasn’t expecting complete accuracy, and I know consistency can be affected by time of day and how you’re standing, but so far the results are unreliable.

I’ll need a few more weeks or months to test the BIA system, measuring at the same time of day, to see if it produces helpful overall trend data. After all, changes in your body composition can take time to register.

Body composition measurement results on the screen of a black Samsung Galaxy Watch 4
David Imel for Engadget

Something else that requires more time for me to get a sense of its usefulness is continuous blood oxygen detection. That’s one of the new sleep-tracking features the upgraded sensors enables, and that data feeds into Samsung’s Sleep Score algorithm, which considers other things like duration and restfulness. In older Galaxy Watches, you can get your blood oxygen saturation (SpO2) readings at-will, but the Watch 4 is able to do a constant measurement overnight. When I woke up, the Watch 4 told me my SpO2 was between 93 and 97 percent, which is slightly lower than I’d like, but could explain why I’ve been so fatigued.

Blood oxygen is one of five factors that go into Samsung’s sleep score, which the company said considers a variety of metrics. Another new thing the Watch 4 can detect this year is snoring. If you want to enable snore detection, you’ll not only have to wear the watch to bed, but also place your phone “on a stable surface near your head” within two feet of your person, and have the bottom of the phone pointing at you. You can choose to have snoring detection on always or only for one night, and you can also opt to record audio to hear your sleep noises the next day. Samsung also gives you the option to delete the recordings after a day, 31 days or 100 days. I don't snore but the potential medical benefits here could be useful for those who do.

The one thing I’d like Samsung to fix is very minor: I couldn’t find the setting to enable snore detection in the Health app until after I had recorded a night of sleep. This was pretty easy to do — I just manually added an entry.

The rest of the updates that the new sensor brings about are less noticeable, like faster heart rate monitoring and updated calorie count algorithms that take into account continuous and discrete pulse readings. These are mostly under the hood, which makes knowing whether there’s a meaningful difference hard to tell until I’ve spent a lot more time with the devices.

A black Samsung Galaxy Watch 4 Classic nestled in some foliage on a planter.

Design and display

Another area where the Watch 4 series got a small upgrade that’s not very obvious is its screen. The larger versions of the devices now have sharper 1.4-inch screens running at 450 x 450, while the smaller models have 1.2-inch panels. They otherwise aren’t much different in size from their predecessors.

I’m used to the Apple Watch SE, and though the Galaxy Watch 4 is actually about 5 grams lighter and its case is only a hair wider, it still felt a little large on my wrist. Its case alone is an acceptable size and weight, but the 20mm strap that Samsung includes is a little stiff out of the box and feels uncomfortable. Over time, though, this should get more pliable and less cuff-like, and you can also swap it out for something softer.

Because it has a physical rotating bezel and a stainless steel case, the Watch 4 Classic is heavier and chunkier than the Watch 4, which has a touch-sensitive ring. While I liked using the mechanical wheel to interact with Tizen Wear OS, it made the device bulky enough that I didn’t want to wear it when working out or going to sleep.

A black Samsung Galaxy Watch 4 on a wrist
David Imel for Engadget

Performance, in use and battery life

Though they look similar to their predecessors, the Watch 4 series boast a significant update inside. They’re powered by new 5nm processors with significantly more storage than before. That additional space should allow you to load more songs on the device, while the processor should make the system fly. And for the most part, the Watch 4s ran smoothly and quickly. The only times I had to sit around waiting for something to happen were when I loaded the Play Store or accidentally triggered Bixby. Speaking of Samsung’s assistant — it’s set to launch when you long-press the top button by default, but you can set it to bring up the power menu instead.

Something I’ve always loved about Galaxy watches is how accurately and quickly they register when I’ve been walking briskly. This year, Samsung updated the software to auto detect a workout after 10 minutes instead of 15. It was gratifying to have a session automatically recorded after I had spent exactly 10 minutes run-walking from a Long Island Railroad platform in Penn station to the Path an avenue away.

The watches are also capable of tracking 95 different workout types, which is nice if you like to get specific with what you’re doing at the gym. I found the running coach mode a little too aggressive with its suggestions, and there are little differences between Samsung and Apple’s systems that would take too much time to spell out, like which brand undercounts distance traveled on a treadmill and which one is too eager to tell me it thinks I’ve stopped walking, for example. But overall the Galaxy Watch 4 are capable activity trackers.

A Thom Browne edition of the Samsung Galaxy Watch 4 laying on its side with greenery in the background.
David Imel for Engadget

Unfortunately, it seems like all the upgrades Samsung added hurt the battery life. Most smartwatches last between one to two days, but for some reason the Galaxy Watch 4 series barely lasts a day. I removed my Watch 4 from the charger at 3pm one afternoon, enabled Always On Display two hours later, and the device died the next day at 5pm.

Wrap up

Short battery life is my biggest issue with the Galaxy Watch 4 and Watch 4 Classic, which are otherwise capable, useful smartwatches. Though some of the newer features like body composition measurement and snore detection might not seem immediately useful, they could provide helpful insight over time. The new Wear OS powered by Samsung isn’t a huge departure from Tizen, which means we’re still getting a powerful, intuitive interface with comprehensive health-tracking features.

Throw in a bigger ecosystem of third-party apps and the Watch 4 series has the potential to offer even more functions. I wish Samsung could make them smaller, thinner and lighter and also extend their runtimes. But — and I know the bar is pretty low here — the Galaxy Watch 4 and Watch 4 Classic are still the best smartwatches for Android users.

Key specs

Sizes: 40mm / 44mm; 42mm / 46mm (Classic)

Display: 1.2-inch 396 x 396 (smaller models); 1.4-inch 450 x 450 (larger models)

Processor: Dual-core 1.18GHz Exynos W920 Dual Core

RAM / Storage: 1.5GB with 16GB storage

Battery size: 247mAh(smaller models) ; 361mAh (larger models)

OS: Wear OS powered by Samsung with One UI Watch 3

Durability and water resistance: 5 ATM, IP68 and MIL-STD-810G

Connectivity: LTE, Bluetooth 5.0, Wi-Fi 802.11a/b/g/n (2.4+5GHz), NFC and GPS/Glonass/Beidou/Galileo

Weight: 25.9 / 30.3 grams; 46.5 / 52 grams (Classic)

Sensors: Samsung BioActive Sensor (Optical Heart Rate + Electrical Heart + Bioelectrical Impedance Analysis), Accelerometer, Barometer, Gyro Sensor, Geomagnetic Sensor, Light Sensor

Photos by David Imel (@DurvidImel)

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