Samsung Galaxy Watch4 Series Can Calculate Your Body Fat Percentage (2024)

(Photo: Molly Flores)

The first smartwatches running the new, unified Google/Samsung Wear OS platform have arrived, and they offer a unique health feature: the ability to calculate your body fat percentage from your wrist.Announced at Samsung's virtual Galaxy Unpacked event on Wednesday (along with new Galaxy Z Flip 3 and Z Fold 3 phones), the Galaxy Watch4 series is available for pre-order now, and will be in stores starting August 27.

The Galaxy Watch4 Classic is the flagship model, with a stainless steel case and the same rotating bezel as the Watch3. It comes in 42mm and 46mm sizes in black or silver, starting at $349.99 for a Bluetooth-only model and $399.99 for one with LTE.

The Galaxy Watch4, which replaces the Galaxy Watch Active line Samsung last updated in 2019, sports a "minimalist" design with a less durable aluminum case. It starts at $249.99 for Bluetooth, or $50 more if you want LTE connectivity. It comes in 40mm and 44mm sizes in black or silver. Samsung will also offer the 40mm version in pink gold and the 44mm model in green.

Samsung Galaxy Watch4 Series Can Calculate Your Body Fat Percentage (1)

Left to right: Galaxy Watch4 Classic, Galaxy Watch4 (Photo: Molly Flores)

Both watches retain the classic round shape of their predecessors, but with thinner cases. Hardware updates include a faster, 5nm processor for smoother scrolling, a higher-resolution display (450 by 450 pixels) for crisper visuals, expanded memory (16GB) for music and app storage, and faster charging (30 minutes of charging provides 10 hours of battery life).

On the downside, battery life doesn't seem to be getting a bump. The Watch3 offers up to around two days of battery life on a charge, while the latest generation will similarly last up to 40 hours, Samsung says.

A Unified Operating System

One of the biggest changes in this generation of Samsung watches is the switch from the company's Tizen mobile operating system, which powers the Watch3 and its predecessors, to the new Wear OS platform.

In May, Google and Samsung announced they were joining forces to merge the Tizen and Wear OS systems, a move intended to help them better compete with the Apple Watch and watchOS. The Watch4 series is the first generation of wearables to run the new unified platform, which features popular Google apps such as Google Maps, as well as Samsung standbys including Samsung Pay, SmartThings, and Bixby. The new Wear OS platform also gives you access to notable third-party apps such as Adidas Running, Calm, Strava, and Spotify.

On Galaxy smartwatches, the new operating system is officially called Wear OS Powered by Samsung. On other smartwatches, it will somewhat confusingly have a different name: Wear OS 3 by Google.

The Galaxy watches also have Samsung's new One UI Watch interface. With One UI Watch, compatible apps downloaded to your phone via Google Play will automatically be installed on your watch. It will also automatically sync certain settings from your phone to your watch, including Do Not Disturb hours and blocked callers. In addition, the watches will support Gesture Controls, allowing you to accept calls by waving your forearm up and down, or to dismiss calls, notifications, and alarms by rotating your wrist twice.

Samsung Galaxy Watch4 Series Can Calculate Your Body Fat Percentage (2)

Galaxy Watch4 rotating bezel (Photo: Molly Flores)

Measure Your Body Composition

On the health front, the Watch4 Series boasts a new three-in-one BioActive Sensor, which can not only read your heart rate and take an ECG, but also calculate your body composition using a process called bioelectric impedance analysis (BIA).

Commonly used in smart scales, BIA involves sending a low-level electrical current through your body to measure your body fat and other metrics. The BIA current moves quickly through tissue that contains a large amount of fluids and electrolytes like muscle and blood, and faces resistance—or impedance—moving through fat.

Samsung Galaxy Watch4 Series Can Calculate Your Body Fat Percentage (3)

Body composition on the Galaxy Watch4 (Photo: Molly Flores)

Samsung says the Watch4's new body composition tool will let you measure your skeletal muscle mass, basal metabolic rate (BMR, or the amount of energy your body uses when at rest), body water percentage, and body fat percentage from your wrist in just 15 seconds.

It's important to note that the small electric current sent through your body during BIA measurement can affect pacemakers. For this reason, you shouldn't use the watch to measure your body composition if you have a pacemaker or any other internal medical device. There's no evidence that this process is dangerous for pregnant women, but Samsung also warns against using the watch to measure your body composition if you're expecting. Also keep in mind that the measurement results may be inaccurate if you're under the age of 20.

The Amazon Halo wristband and app-based wellness service also lets you take a body fat scan, a feature we found a bit creepy in testing. Amazon's version doesn't use any sensors in the band, but instead uses your smartphone's camera along with computer vision and machine learning technology to analyze the shape of your body and calculate your body fat percentage. Amazon says its body fat percentage tool is nearly twice as accurate as smart scales that use BIA to estimate your body fat, though we can't verify those claims.

Track Your Snoring

At night, the Watch4 and a compatible smartphone will track a fairly uncommon sleeping metric: snoring.

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To record this, Samsung says you need to wear the watch to bed and place your phone on a stable surface near your head, with the microphone on the bottom of the handset pointed toward you. The watch will track your sleep duration and overnight blood oxygen saturation (SpO2) level, while your smartphone monitors your snoring.

In the morning, you'll see your SpO2 level alongside your snoring data in the Samsung Health app. For reference, the second-generation Google Nest Hub smart display offers a similar snore-tracking feature, but this is the first time we're seeing it on a watch (or at least in conjunction with a watch).

Samsung Galaxy Watch4 Series Can Calculate Your Body Fat Percentage (6)

Buttons on the Galaxy Watch4 (Photo: Molly Flores)

As for other health and fitness features, Samsung says the Watch4 series will offer faster automatic workout recognition and more accurate tracking. It also features guided workouts and group challenges to help you stay motivated and accountable. In addition, you'll be able to connect the watch with compatible Samsung smart TVs to see your calorie counts and heart rate on the big screen when following along with workout videos.

“We understand the path to wellness is different for everyone, so we built a robust suite of health and wellness features to give people a deeper and more helpful understanding of their overall fitness," Dr. TM Roh, president of Samsung's mobile communications business, said in a statement.

Samsung is offering a $50 credit if you pre-order the Watch4 or the Watch4 Classic between August 11 and August 26, 2021. The company also plans to offer a limited edition rhodium-plated Watch4, created in collaboration with fashion designer Thom Browne, in September.

Samsung’s earlier Tizen-based smartwatches have earned high marks from PCMag. The Watch3 got four out of five stars last fall thanks to its ECG app and trip detection. Stay tuned for our reviews of the Watch4 and Watch 4 Classic.

Samsung Galaxy Watch4 Series Can Calculate Your Body Fat Percentage (7)

Samsung Galaxy Watch4 Series Can Calculate Your Body Fat Percentage (8) Samsung Galaxy Z Flip 3 & Z Fold 3: What you need to know

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About Angela Moscaritolo

Managing Editor, Consumer Electronics

I'm PCMag's managing editor for consumer electronics, overseeing an experienced team of analysts covering smart home, home entertainment, wearables, fitness and health tech, and various other product categories. I have been with PCMag for more than 10 years, and in that time have written more than 6,000 articles and reviews for the site. I previously served as an analyst focused on smart home and wearable devices, and before that I was a reporter covering consumer tech news. I'm also a yoga instructor, and have been actively teaching group and private classes for nearly a decade.

Prior to joining PCMag, I was a reporter for SC Magazine, focusing on hackers and computer security. I earned a BS in journalism from West Virginia University, and started my career writing for newspapers in New Jersey, Pennsylvania, and West Virginia.

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