Data accuracy

COROS works hard to provide the most accurate data as possible utilizing the unique hardware/software designs and proprietary algorithms. We have confidence in our data accuracy when compared with other brands. We have listed below the potential sources for data that is less than ideal.


Satellite conditions, weather, tall buildings, heavy tree coverage and other sources may interfere with the GPS signal and affect the GPS accuracy. You may change the GPS mode and see which one provides a better result. When GPS signal is weak or lost, COROS’s Intelligent Stride algorithm along with motion sensors will kick in to maintain a good tracking accuracy. Every outdoor run and calibrated indoor run improves the algorithm to better track your next workout.

Related topics
GPS Accuracy – What’s right and what’s not
COROS App – GPS Satellite Data
UltraMax GPS mode

Heart rate

COROS watches use optical wrist-based heart rate sensor to track daily and workout heart rate data. There might be a few seconds delay when viewing your real-time HR data on the watch due to data processing. COROS algorithms are carefully calibrated to ensure the best accuracy under most circumstances including under water. However, the optical wrist-based heart rate sensor may not work properly over tattoos. There are many factors that can cause the HR data to deviate from accurate readings. These factors include wrist temperature, tightness of the watch band, excessive sweat/water, watch location on the wrist, tattoo, skin color and hair, blood vessel size, etc. In addition, the heart rate reading results from optical wrist-based heart rate sensors may vary on an individual basis.

Alternatively, you can pair an ANT+ supported HR chest strap with your COROS watch. Click to learn more at Pair with an ANT+ enabled accessory.


COROS watches rely solely on barometric altimeter when calculating the elevation gain/loss. Factors like weather changes and pressurized environments can affect the readings. Outdoor workouts longer than 6 hours are prone to be affected by changes of air pressure even if the elevation remains the same.

SpO2 oximeter (available on VERTIX)

COROS development team successfully applied wrist-based SpO2 detection technology on watches and achieved accuracy comparable to medical fingertip measurement when remain stable at the end of 2017.

In order to record accurate readings, please place the watch tightly against your wrist and next to the wrist bone. During the measurement, please keep your forearm horizontal and still.

When temperature is low, blood vessels will shrink and your COROS watch may fail to detect SpO2 readings. When low temperature notification shows up during the measurement, please bring up the temperate of your wrist and resume the measurement.

COROS trainer and fitness related data

Unlike some of the brands that are using technologies provided by data vendors directly, COROS works with a partner to co-develop the COROS trainer and other fitness data. The workload between COROS and our partner is shared almost equally. Our partner has its original lab designs and algorithms while COROS provides feature designs, user case applications and real-world testing. The development and improvement is an on-going process and we are confident with the in-house development process. COROS is aiming to create a better and more accurate platform for the sports community.

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