What is the Maximum Heart Rate of a Kardia EKG? Updated January 11, 2018 15:55 The maximum heart rate calculated from a Kardia EKG is 300 bpm. Related articles How do I view, print or share my EKG as a PDF? What does it mean when my heart rate bars are orange versus green? What happens to my heart health data after my free 30-day Premium trial ends? (recordings, blood pressure, weight, activity) What is the Gain of the EKG display in Kardia apps? What are the AF, Normal and Interference Detectors?