CMF Watch 3 Pro review on World Heart Day: How good are its heart-rate and health-tracking features?
With World Heart Day falling on 29 September, smartwatches are once again drawing attention to the health data they can collect from the wrist. The CMF Watch 3 Pro adds a new optical heart-rate sensor, 24-hour monitoring, sleep-tracking and the Activity Score, which is based on heart-rate data.
Nothing’s sub-brand, CMF, released the Watch 3 Pro as the successor to the Watch Pro 2. It features a 1.43-inch AMOLED screen, dual-band GPS, Bluetooth calling, 131 sports modes, and a 350mAh battery. The watch is priced at Rs. 7,999 in India. After using it for a few days to track workouts, runs and sleep, here is how its health features performed.
Heart rate tracking
One of the key features of the new CMF Watch 3 Pro is its new optical heart-rate sensor. Nothing claims the sensor detects subtler blood flow changes and can provide up to 7% more accurate blood flow readings during activity and up to 3.6% more accurate readings during rest than previous generations.
When I used the watch during rest and exercise, I got heart rate measurements that were fairly similar to those from a pulse oximeter. The readings were also stable enough to track changes in heart rate during exercise.
The watch automatically monitors the user’s heart rate and tracks it for 24 hours a day. It also enables users to configure high- and low-resting-heart-rate warnings. Frequencies of automatic measurements can be adjusted via the Nothing X app.
All of the features of heart rate, SpO₂ and stress are clearly marked as ‘for health and personal reference’ and not intended to be used for medical diagnosis or clinical monitoring by CMF.
SpOâ‚‚ and stress data
The term ‘heart rate’ is not the only thing you should look at. The Watch 3 Pro can also monitor the user’s blood oxygen and stress levels. The 24-hour SpOâ‚‚ is available in the Nothing X app, and the stress monitoring option can be set to take measurements at regular intervals. The SpOâ‚‚ values were generally similar to those obtained from a pulse oximeter during my use. However, continuous blood oxygen and stress monitoring has a battery cost.
The Activity Score also converts activity and heart rate data into an Activity Score. The score uses heart rate data and MET values to provide users with a single measure of daily activity. It also provides a 7-day view, allowing you to see whether activity levels are increasing or decreasing.
Sleep tracking
Sleep is another area where the Watch 3 Pro performed well during my testing. It measured my overall sleep and distinguished among sleep stages (REM, core, and deep).
The watch can also detect naps. Nothing says it’s enhanced sleep tracking, which combines improved motion sensing with higher-frequency heart-rate sampling.
The number is not necessarily a reflection of a single night’s performance but more about consistency over time. The Nothing X app offers a longer-term view of the data and makes it easier to compare sleep duration and patterns across multiple days.
Dual-band GPS
The most significant hardware upgrade is dual-band GPS for fitness tracking. L1 and L5 signals are supported along with GPS-related signals such as GLONASS, Galileo, BeiDou and QZSS. This made a clear difference during my runs. GPS locked in within seconds and was stable while outdoors in a session.
The watch also offers a total of 131 sports modes, VOâ‚‚ max, training load and recovery data. The Custom Running Coach is useful for creating an 8- to 16-week plan, but it’s more effective for shorter-distance runners who are not training for longer-distance races.
One omission is swim tracking. The watch is not as comprehensive as some of its rivals when it comes to swimming data and tracking, despite its 131 sports modes.
Display
The Watch 3 Pro maintains the circular design of its predecessor but adds a 1.43-inch display. It features a 466 x 466-pixel AMOLED screen with a 60 Hz refresh rate and up to 670 nits of brightness. The screen remained readable outdoors during my use.
The precision-milled metal frame adds a higher level of quality to the watch than its budget-friendly retail price would imply. The 47mm body is somewhat large, and a rotating crown makes scrolling the interface easier.
Nothing X
The Watch 3 Pro has been designed to pair with the new central companion app, CMF’s Nothing X. All health data, watch faces, workout history and device settings are accessible in a single place.
The software has the familiar Nothing-style dot-matrix visual language. Over 120 watch faces, including animated and Always-On Display. The watch can also produce photo and video avatars, and features like voice notes, Essential News, and ChatGPT extend beyond fitness tracking.
The built-in speaker and mic also enable you to communicate via Bluetooth. The call noise reduction system is trained on over 100,000 voice samples, and up to 30 contacts can be stored for quick access.
Battery
The Watch 3 Pro has a 350 mAh battery. It has a typical use of up to 13 days, heavy use of up to 10 days and supports up to 4.5 days of heavy use and AOD-enabled use.
With 24/7 tracking of heart rate, SpOâ‚‚, and stress, the watch lasted about six days, GPS was used for about 5.5 hours, and a few Bluetooth calls were made. The other testing scenario with 24/7 health tracking/notification led to approximately seven days of use.
A full charge took about 90 minutes with the bundled magnetic charger. That’s not really quick, but since it’s at a weekly endurance level, daily charging isn’t required.
CMF Watch 3 Pro verdict
The CMF Watch 3 Pro’s ability to track health and fitness makes it a stronger contender than its flashy smartwatch features. With its new heart-rate sensor, continuous monitoring capabilities and Activity Score, it can be helpful for those who want to track their activity and heart-rate patterns throughout the day. The sleep tracking and dual-band GPS add practical value, especially for users who exercise regularly.
Continuous health readings may shorten battery life, and the running coach may be focused on shorter distance objectives.
At Rs. 7,999, the Watch 3 Pro is a smartwatch packed with features for its class, particularly heart and activity tracking.
For World Heart Day, the most relevant takeaway may be this: a smartwatch can make health data easier to see every day, but the real benefit comes from using that information to understand your habits and notice changes over time.
I rate the CMF Watch 3 Pro 8.3/10.
