Accuracy of the heart-rate monitoring function varies with a number of factors. Wearing the AXTRO Fit 3 properly will reduce occurrences of inaccurate readings. Check that the tracker is worn firmly above the wrist. A good gauge would be two-fingers’ width above the wrist bone.
The heart-rate sensor of the AXTRO Fit 3 has to be in full contact with the skin. Ensure that there are no gaps between the sensor and the skin. Consider wiping off perspiration, if any, from skin that is in contact with the tracker sensor for a better reading.