The Apple Watch Series 12 trailed behind at 1.94 bpm, while the Fitbit Air (2.96 bpm), WHOOP MG (3.14 bpm), Garmin Forerunner 970 (3.18 bpm) and Oura Ring 5 (5.21 bpm) recorded wider variance.
Temple logged an overall mean absolute error (MAE) of 1.18 beats per minute (bpm).
The Apple Watch Series 12 trailed behind at 1.94 bpm, while the Fitbit Air (2.96 bpm), WHOOP MG (3.14 bpm), Garmin Forerunner 970 (3.18 bpm) and Oura Ring 5 (5.21 bpm) recorded wider variance.
In Zone 5 alone, its margin fell to 0.95 bpm, with zero test subjects exceeding a 5 bpm average error.
The temple site delivered the lowest overall error (3.50 bpm), comfortably outperforming sensor placements on the chest (5.10 bpm), thumb (5.62 bpm) and wrist (6.03 bpm).
MUMBAI: When Zomato chief executive officer Deepinder Goyal rolled out his new performance brand Temple, he did not just pitch a new gadget, he called out the underlying flaw of the entire wearable market. Wrist-worn fitness trackers have long dominated the industry, but they struggle with a glaring weakness: whole-body motion, wrist tendon flex and arm swing throw off optical sensors precisely when athletes need precision most.
Temple’s answer is a shift in anatomy. Designed as a compact patch worn directly on the forehead over the superficial temporal artery, the device bypasses the physical interference that plagues traditional smartwatches and smart rings.
The lab results: Forehead vs. Wrist and Finger
In an internal trial benchmarking six optical wearables against a taped chest ECG strap reference, Temple’s head-mounted sensor consistently maintained single-digit error margins across all exertion levels:
All-around accuracy: Temple logged an overall mean absolute error (MAE) of 1.18 beats per minute (bpm). The Apple Watch Series 12 trailed behind at 1.94 bpm, while the Fitbit Air (2.96 bpm), WHOOP MG (3.14 bpm), Garmin Forerunner 970 (3.18 bpm) and Oura Ring 5 (5.21 bpm) recorded wider variance.
Temple logged an overall mean absolute error (MAE) of 1.18 beats per minute (bpm). The Apple Watch Series 12 trailed behind at 1.94 bpm, while the Fitbit Air (2.96 bpm), WHOOP MG (3.14 bpm), Garmin Forerunner 970 (3.18 bpm) and Oura Ring 5 (5.21 bpm) recorded wider variance. High-intensity stability: In Zones 4 and 5—where peak exertion often causes optical dropouts—Temple recorded an MAE of 1.16 bpm. In Zone 5 alone, its margin fell to 0.95 bpm, with zero test subjects exceeding a 5 bpm average error.
In Zones 4 and 5—where peak exertion often causes optical dropouts—Temple recorded an MAE of 1.16 bpm. In Zone 5 alone, its margin fell to 0.95 bpm, with zero test subjects exceeding a 5 bpm average error. Site-by-site validation: To test if the location itself was key, researchers ran identical Polar optical sensors simultaneously at four body sites. The temple site delivered the lowest overall error (3.50 bpm), comfortably outperforming sensor placements on the chest (5.10 bpm), thumb (5.62 bpm) and wrist (6.03 bpm).
Sensor Placement & Device Overall Mean Absolute Error (MAE) Large Errors (>5 bpm off) Temple (Forehead) 1.18 bpm 1.8 per cent Apple Watch Series 12 (Wrist/Forearm) 1.94 bpm 9.0 per cent Fitbit Air (Wrist/Forearm) 2.96 bpm 17.3 per cent WHOOP MG (Wrist/Forearm) 3.14 bpm 23.5 per cent Garmin Forerunner 970 (Wrist/Forearm) 3.18 bpm 21.9 per cent Oura Ring 5 (Finger) 5.21 bpm 36.1 per cent
Why location beats hardware iterations
Most wearable makers attempt to improve tracking accuracy by updating software algorithms or adding extra light-emitting diodes to wrist modules. Temple’s white paper suggests the real bottleneck is where the device sits.
Because the temple area sits directly over major blood vessels and remains clear of heavy muscle flex or skin clamping during hard sprints, optical sensors receive a cleaner pulse signal. Combined with a medical-grade adhesive grip that prevents movement lag, Temple aims to prove that fixing wearable accuracy is less about changing the code and more about changing the spot.
