Although there are many different options when it comes to upgrading your Android phone, there are far fewer top choices of Android smartwatch. For the past few years, the Google Pixel Watch and Samsung Galaxy Watch range have been the go-to wearables for those who don’t have an iPhone, but I’m happy to find that the new OnePlus Watch 3 could be the very best of the Android bunch.

The OnePlus Watch 3 boasts five day battery life, an unheard of figure in a world where you have to charge most other smartwatches every day. In testing, I found the OnePlus Watch 3 can achieve this feat if you leave all the default settings alone. This doesn’t take away any key functionality, and you don’t have to use any power saving modes to get this battery life, though the longevity drops once you enable some other features such as blood oxygen monitoring or the always-on display.

Although I prefer the design of the minimalist Pixel Watch 3, the OnePlus Watch 3 looks great on the wrist thanks to its classic look with a new titanium bezel with minute markers that adds a bit of class compared to the OnePlus Watch 2. The crown on that watch rotated but didn’t do anything, a major bummer that OnePlus has fixed this time - the crown scrolls menus like it does on the Pixel Watch and Apple Watch with delightful haptic feedback.

It’s a shame OnePlus only offers one size, though. The 47mm stainless steel casing is large and although I don’t mind it on my big wrists, both Google and Samsung offer their smartwatches in two sizes. A smaller option would be nice, as would the option to buy a cellular model for eSIM connectivity. The OnePlus Watch 3 is a flat £319 in either Emerald Titanium (silver with green strap) or Obsidian Titanium (black with black strap) and Bluetooth connectivity only, so you always need to be connected to your smartphone to receive notifications or use data services for calls, texts and apps.

The circular 1.5-inchAMOLED screen is protected with sapphire crystal glass for scratch resistance and there’s an IP68 dust and water resistance so you can go swimming with it on or dive to 50 metres. The 22mm strap is also easy to remove, and OnePlus sells spares and other options.

The real cleverness on the Watch 3 is in OnePlus’s use of two processors. You get both the Snapdragon W5 for running Google’s WearOS 5 as well as a BES2800 that runs what is known as a Real-Time Operating System (RTOS). This means the former chip is used when you are using apps or doing intensive tasks such as a GPS tracked run, but then the latter chip ticks away handling background tasks. This is a very efficient set up that allows for the five day battery life, with a 631mAh battery inside using Silicon NanoStack tech that’s also more efficient than traditional lithium-ion cells.

I found the watch lasted five days long on all the default settings. If you want to use the always-on display, for example, a pop up warns you this will knock two days off the battery life. That still makes this a three day watch, but other warnings surface if you turn on snore or breathing detection for sleep tracking and other advanced health features.

There’s also a power saver mode that OnePlus says kills all but the workout and health functions to eke out up to 16 days of battery life. This is a sensible option to provide and is great if you forget your charger or want to go on a long run and are low on juice. Topping up takes 80 minutes from empty depending on your charger, with official OnePlus chargers working fastest (there's no charger in the box). I love the tiny charging puck with a USB-C port that you can carry around easily and snap onto the back of the watch to charge with any USB-C charger.

The electrocardiogram (ECG) functionality is also sure to dent battery life, but I couldn’t test this as it’s not live in the UK yet. OnePlus told me the ECG, which tracks heart health, will be switched on “from Q3 2025”, so you might want to wait to see if that happens. US buyers will never get it, according to OnePlus. All models get NFC for mobile payments via the Google Wallet app.

The WearOS software is zippy, but looks nothing like the Google-ified look of the Pixel Watch 3. OnePlus’s skin is not ugly, but it is a little more colourful and, to a degree, toy-like, but it has more personality than some wearables. The plethora of watch faces with many customisable complications is also great to see.

Swiping left or right from the home screen shows you different tiles for things like weather, sleep tracking, activity, heart rate and wellness. The latter is a vague summary of how you are doing throughout the day. “Learn to unwind. Stress is only temporary”, one notification told me on a particularly stressful day. To be fair, the watch could somehow tell I was a little tense, but the wellness tracking in general is a little vague.

Because the watch uses WearOS you can download several third party apps including Spotify, Strava, All Trails and Nike Run Club. Many are fitness related. They work well, and you can download Spotify albums and playlists for offline listening if you want to go on a run without your phone by pairing Bluetooth headphones directly to the watch.

I found doing this while tracking an outdoor run via GPS worked well, and the route tracking was pleasingly accurate, along with the heart rate data. You have to install OnePlus’s OHealth to pair the watch to your phone and view fitness data as well as do things such as change watch face or tweak notifications. I easily linked the app to Strava so my runs uploaded automatically, but you can actually do most other things on the watch itself and leave the app alone.

I tested the watch with the OnePlus 13 and Samsung Galaxy S25 and was pleased to find I didn’t lose any major functionality on a non-OnePlus phone. Samsung restricts some features on its Galaxy Watch models to only work with Galaxy phones, something I applaud OnePlus for avoiding, making the Watch 3 a great choice for Android owners across the board.

The big downside to the OnePlus Watch 3 is that it’s only guaranteed two years of software updates and two years of security patches. Phones are generally better updated, with at least five to seven years now for most major Android devices, while watches generally aren’t promised as long, but two years is particularly stingy. Samsung says it will update the latest Galaxy Watch 7 for at least four years, while the Pixel Watch 3 is getting three.

All three firms could do better, but it means the OnePlus Watch 3 will be stuck with whatever software it gets in 2027, which is at odds with its excellent battery life that will decline over time but likely make it actually usable day to day for longer than its rivals. You’ll have to be OK with a watch that will end up not being updated, even if it’s still ticking for several days between charges in a couple of years.

Overall, the OnePlus Watch 3 excels on all fronts, making it a formidable rival to the Google and Samsung equivalents. It has the best battery life of any Android smartwatch, full WearOS app support, good looks, and smooth performance that will please most buyers. The fact its features work across all Android phones is a boon, too.

It’s just a shame it only comes in one large size and will only get software updates for two years. But if these things don’t bother you, the OnePlus Watch 3 is one of the best smartwatches going.

The OnePlus Watch 3 is available to buy now from OnePlus.