OnePlus Watch 3 Review: The Best Battery Life of Any Android Smartwatch

In my ten plus years of testing smartwatches, I’ve never had to actively try to drain a battery. That changed when I strapped on the $330 OnePlus Watch 3. Five days into my battery test, after charging it to 100%, this watch was still going strong; tracking my sleep, runs and vitals without missing a beat.

I’ll admit that the Watch 3 didn’t make the most favorable first impression, with its clearly masculine design and oversized screen that practically swallowed up my normal-sized wrist. I half-expected to write it off as just another mid-range smartwatch destined to collect dust in a drawer. But it turns out, I’m willing to overlook a few things like the size and lack of ECG functionality for exceptional battery life.

Four years after its shaky debut, OnePlus’ underdog smartwatch has matured into a true competitor to Samsung and Pixel watches, delivering the best battery life I’ve ever tested on a Wear OS device—all while packing solid health features into a subdued and elegant (albeit large) design.

Battery life takes center stage

Unlike the original $160 OnePlus Watch and last year’s $180 Watch 2R, whose main draw was affordability, the Watch 3 shifts the focus from price to performance. With its $330 price tag, OnePlus is positioning it as a premium flagship device, competing directly with similarly priced Wear OS watches like the Google Pixel Watch 3 and Samsung Galaxy Watch 7. What truly sets it apart is its battery that  is larger than its predecessor at 631mAh (vs 500mAh on the Watch 2).

The Watch 3 uses a dual chipset system to split up tasks and optimize power consumption and get even more out of its big battery. The Snapdragon W5 processor focuses on powering app usage, while the BES2800 MCU Efficiency chip handles background tasks that don’t use as much power. 

Though skeptical at first, my two weeks of testing confirmed that the OnePlus Watch 3 truly delivers on its five-day battery claim. I did three GPS workouts, one of which was an hour and a half hike, and six full nights of sleep tracking. Even its fiercest Wear OS competitors would struggle to last three days without resorting to using a low power mode that strips the watch of its ‘smart’ features and turns it into a glorified digital clock. The only caveat with the Watch 3 is that it remains on the default “Smart mode” to achieve the full five days. This mode has a raise-to-wake screen and requires using one of OnePlus’ official watch faces. I typically prefer an always-on display with a busier watch face filled with my most-used complications and shortcuts which would likely bring the battery life closer to three days – still a feat considering how bright the screen is, even in dormant mode.

When I first started testing the watch, I made the mistake of opting for a non-OnePlus watch face with a three out of three rating on the battery drain scale and still managed to squeeze in four days worth of charge. While I haven’t tested the claim yet, OnePlus says the watch can make it to 16 days in “Power Save” leaving it mostly as a dedicated fitness tracker rather than a full-featured smartwatch. 

Of course everyone has a different version of what “normal” use is, and when you finally charge it, the Watch 3 goes from zero to 100% in just under an hour. 

Polished design, with one giant oversight 

The OnePlus Watch 3 has a sleek stainless steel design with a rotating crown that has an easy-to-grip texture making it simple to turn. There’s a slim titanium bezel framing the screen that’s reminiscent of the old rotating bezels on the early Samsung watches that I loved. Sadly this one doesn’t move, but I like how it elevates the design, making it look less like a giant circular 1.5-inch AMOLED display strapped to my wrist. 

Objectively, this is a good-looking watch. But as a woman with an average-sized wrist, this watch feels huge and clearly not designed with me in mind. I don’t need a rose gold frame and a sparkly pink band, I just wish it had more inclusive sizing options and maybe a classic gold option. The watch comes in a black or silver finish, with interchangeable rubber watch bands in moss green, black or Nordic blue that scream “made for men.” If the Watch 3’s size and bands were its only exclusion of female representation, I might be able to write it off. But it’s missing one more feature I’ve come to expect on a smartwatch: menstrual tracking.

Robust health features, minus period tracking

It’s a big miss that OnePlus didn’t include menstrual tracking on the Watch 3. Menstrual tracking is now a standard feature in newer Apple Watch and Garmin smartwatches. The Watch 3 has pretty much every other health feature including temperature tracking, which can be used to help identify a woman’s ovulation window.  

Oversight aside, it’s clear that OnePlus is investing heavily in health tracking. Beyond basic heart rate and sleep data, the watch measures more advanced metrics like cardiovascular health, blood oxygen levels, wrist temperature, and overall well-being, including emotional and stress levels. It also features an electrocardiogram (ECG), though as of publication, OnePlus has not sought FDA approval, meaning the feature will not be active in the US or Canada.

While not medical-grade, OnePlus claims that the Watch 3’s health metrics are more accurate than in previous models, thanks to upgraded sensors, refined algorithms, and improved cover glass over the back sensors for clearer readings.

The Watch 3 also debuts a 60-second health check-in, a feature that checks all your vitals at once by pressing your finger on the watch’s bottom button to create a circuit. My first health check-in was concerning and displayed a red exclamation mark with the word “abnormal” next to it. It turns out that all my vitals were in range, but my sleep score was so low that it skewed the results. 

Battery life is a game changer for sleep tracking 

As a low-key sleep tracking hater, I never realized just how much battery life factored into my frustration. As a parent of young kids, I already know I’m not getting enough sleep and seeing a bad sleep report first thing in the morning just sets me up for a day of dragging and self-pity. I feel the same way about wellness checks. Not having to take off the watch for five consecutive days made me more inclined to track my sleep, and I may have even learned a thing or two about my sleep patterns. 

The Watch 3’s long battery let me collapse into bed at the end of the day without worrying whether my watch had enough charge to last through the night. The watch even tracked my sleep on night six, despite being down to 10% battery in “Power save” mode. The watch also has an option to monitor SpO2 (blood oxygen levels) and breathing patterns during sleep to help identify more serious breathing issues, but it will drain the battery faster and needs to be activated manually from either the watch or the mobile app.

According to a recent interview from Wareable, OnePlus is already in the process of seeking FDA approval for sleep apnea detection which may make the extra battery drain worthwhile.

A worthy fitness companion to put you through the paces 

In terms of fitness, the OnePlus Watch 3 covers all the basics, with more than 100 different sports modes, six of which it detects automatically: running, walking, rowing, elliptical machine, cycling, and swimming. It also offers a “professional” mode for 11 sports that keep tabs of more nuanced metrics related to that sport. For runners it’s things like form and foot balance, and for tennis players it’s swing speed and stroke. While it may be overkill for most, as a runner who recently learned how to leverage heart rate zones to intensify workouts, I was excited to nerd out on the additional metrics. 

I used it during my usual three-mile run and learned that while I have excellent balance between my right and left feet, my ground contact time (how long my foot stays on the ground) and vertical oscillation (how much I bounce) could use some improvement to make my runs more efficient and less injury-prone. The app provides context for the additional data, but it be overwhelming, and you have to dig around for a definition of each metric. I was also left longing for more actionable tips for improving my stats.

The One Plus Watch 3’s heart rate tracking kept up with my Polar chest strap (the gold standard for athletes), with a lag of just a second or two and a one point difference in average heart rate between the chest strap and the watch. Heart rate serves as a baseline for many of the fitness metrics on the Watch 3. However, once I started running uphill and inching closer to my maximum heart rate, I noticed that lag time increased to about 25 seconds between what the chest strap was showing (on my phone) and the number on my wrist. I tried tightening the band, but it only helped temporarily. By the end of my workout, the watch showed that I had stayed in my peak heart rate zone for 19 seconds, while the chest strap recorded me in this zone for about three and a half minutes.

The lag could be partially due to the sensor’s proximity to the heart (versus the wrist). Sweat and arm movement could also interfere with an accurate read — a problem for most smartwatches. Whatever the case, heart rate accuracy could be an issue if you use it for for high-intensity sports or more serious training. You’re still better off using a chest strap.

Another key feature for outdoor sports enthusiasts is its dual-frequency GPS tracking system, which OnePlus claims can position you accurately even in challenging environments, such as crowded cities surrounded by high rises. I live in a rural environment that’s more sheep than skyscrapers, so I haven’t been able to fully test this claim. It did position me perfectly on my hour and a half hike through oak trees and vineyards.

With an IP69 rating, the OnePlus Watch 3 is also water-resistant up to 50 meters.

Weighed down by Wear OS and limited updates

The Watch 3 runs on Wear OS 5, with a few additional OnePlus design and navigation features. You can customize the rotating crown and side button as shortcuts, but everything else will feel like a standard Wear OS watch packed with whatever apps you’ve downloaded. 

The interface of the Watch 3 feels sluggish, with a slight lag in response time, though it became easier to use as I got more familiar with the swipe and tap directions. The UI isn’t exactly intuitive, either. For example, the battery icon shows the remaining charge but doesn’t let you switch to “Smart” or “Power Save” mode which after some trial and error I found hidden behind what looks like an infinity icon. There are also three ways to access the workout screen, but only one of those ways will allow you to add a workout type (through the list of apps). This may be more of a Wear OS navigation issue than a OnePlus problem, but it’s still cumbersome.

Additionally, you’ll need to download the separate OHealth app to your phone to access the watch’s full range of health tracking features. The app itself is visually appealing and intuitive, but the setup wasn’t seamless. It took multiple tries to sync with my Google Health data. It’s worth noting however that I was using a developers version of the OHealth app, so setup may be smoother on the public version.

The biggest downside of the OnePlus Watch 3, however, is that it only guarantees two years of software and security updates, while some of its competitors like Samsung offer up to five. This means the watch, despite its impressive battery life, could become obsolete much sooner.

Solid battery life and features tip the scale

If you’re looking for a watch with a smaller footprint or a more feminine design, then the OnePlus Watch 3 may not be your best bet. But if battery life is at the top of your wishlist, this is one Android smartwatch that’s definitely worth considering. The OnePlus Watch 3 is a premium smartwatch at a mid-range price point that checks nearly all the boxes for health and fitness features, and outlasts most competitors when it comes to battery life – just not when it comes to software updates. The OnePlus Watch 3 is now available for $330 on the OnePlus website.