Tag Heuer is taking a risk with its new Connected Calibre E5 smartwatch by leaving Google and Wear OS behind, and going it alone with its own Tag Heuer OS software.
While at first it may seem like an odd decision to say goodbye to Wear OS, the more you understand the reasons why, the more it makes sense. The Calibre E5 moves on from the old way of doing things, and after spending some time with the watches and software, it has me really intrigued.
Why Tag Heuer OS?
Sorry Android users, it’s not about you
Tag Heuer OS is the first smartwatch operating system to be Made for iPhone (MFI) certified, which is key to understanding why Tag Heuer hasn’t used Wear OS for the new model. Don’t worry Android phone owners, the Calibre E5 still works with your phone, but according to Tag Heuer a massive 70% of people who buy the brand’s smartwatches use an iPhone.
The decision took me by surprise. Tag Heuer was one of the first brands to embrace Wear OS 3, when Google allowed the connecting app to be customized, providing smartwatch makers a way to personalize the experience. However, since then, Google has made Wear OS less open, including special partnerships with Samsung for Wear OS 5, and naturally focusing on its own Pixel Watch smartwatch, while also putting less emphasis on iOS over time.
When 70% of your audience uses an iPhone, this causes immediate problems, and as a relatively small smartwatch manufacturer, Tag Heuer took it as a sign to try something new. A team of 60 in-house engineers have worked on the Calibre E5 and its software, leaning on experience from LVMH stablemate Louis Vuitton’s recent Tambor Horizon Light Up smartwatch, to create Tag Heuer OS. The MFI certification makes fast, reliable pairing possible with iOS, and the ability to integrate Siri and features like taking calls. While the focus is on iOS, Android owners won’t miss out on any features.
What’s Tag Heuer OS like to use?
It’s different, in a good way
Anyone used to Wear OS or Watch OS will immediately notice how swipes on the touchscreen have less priority in Tag Heuer OS, and the two side buttons and crown are far more integral to navigating the software. The top button opens a menu, which is then navigated by touch or by rotating the crown, while the lower button opens quick settings.
Swiping up on the screen shows your notifications, and a downward swipe shows a series of widgets. At launch, these widgets will include fitness and health data along with the weather, and other widgets will be added over time. A long press of the crown brings up the watch face options, which include a huge range of faces inspired by Tag Heuer watches from the Formula One, Aquaracer, and Carrera models.
Once you’re used to not swiping on the screen as much, Tag Heuer OS is logical and clearly laid out. Each option has clear text to tell you what it does, and the icons are big enough to tap, indicating the system has been well thought out. There’s some pleasing haptic feedback when navigating the menus, and the operating system appeared fast and smooth in my short test. I like how Tag Heuer has made better use of the physical buttons, which is how we interact with its non-smartwatches.
The main problem Tag Heuer will face is the lack of app store access. There’s no Google Play, and Apple keeps the App Store for the Apple Watch. If you want Spotify, a specific running app, Gmail, Google Maps, or anything else, you’re going to have to look elsewhere for your smartwatch fix. The positive spin on this is Tag Heuer has been able to increase efficiency, as it doesn’t have to deal with variables from third-party apps.
Two Calibre E5 sizes
Suitable for most wrists
That’s the software covered, but what about the hardware. Tag Heuer prides itself on designing the Calibre E5 in-house, making it a true Tag Heuer watch. The 45mm case size returns, and it’s joined by a new 40mm case size. Both come in stainless steel, while a titanium model is available in the 45mm size, along with a choice of leather, rubber, metal, and velcro straps.
The 45mm suited my 6.5-inch wrist best, with the 40mm looking a little too small for my personal taste, but it’ll be perfect for some. Sapphire crystal covers the screen, which is pressed right up against it for a genuinely watch-like style. It was very bright, and the Tag Heuer watch faces look superb. The new velcro straps are highly adjustable and very comfortable.
There’s a heart rate sensor on the back of the Calibre E5, special running and golf tracking apps, dual-frequency GPS, and Strava integration. Unfortunately, the Calibre E5 won’t launch with sleep tracking, including key metrics like blood oxygen, heart rate variability (HRV) and breathing rate. These features will arrive in an update coming in early 2026.
This is a shame, and while understandable given a modest team is responsible for the software, we never recommend buying a device based on promised future features, so if sleep tracking is important to you, it may be worth waiting. This aside, Tag Heuer OS shows considerable promise through its intuitive design, the clever decision to rely more on physical buttons for control, and the beautiful watch faces.
What about the rest of the tech?
Longer battery life
Tag Heuer’s control over the software enables it to improve efficiency and lengthen battery life compared to what’s normally possible from a Wear OS smartwatch. Tag Heuer expects two days from a single charge for the 45mm version, and around a day-and-a-half on the 40mm. There’s also a Low Power mode which adds about another day’s battery life.
Other key specification details include the Qualcomm Snapdragon 5100+ processor, a 1.39-inch AMOLED screen on the 45mm version and a 1.20-inch AMOLED on the 40mm model, dual-band GPS, Bluetooth 5.3, Wi-Fi, and 50 meters of water resistance.