What is the Maximum Heart Rate of a Kardia EKG? Updated February 14, 2018 04:41 The maximum heart rate calculated from a Kardia EKG is 300 bpm. Related articles What does it mean if my EKG is Unclassified? What are the AF, Normal and Interference Detectors? What does it mean when my heart rate bars are orange versus green? How do I view, print or share my EKG as a PDF? What is the Paper Speed of the Kardia EKGs recorded with Kardia devices?