How to Calculate Heart Rate Variability

Your heart typically beats in a regular, steady rhythm at a consistent rate. Heart rate variability occurs when the heart does not beat in a consistent rhythm. The American Heart Association says that cardiologists can draw incorrect conclusions when they measure an irregular heart beat. To reduce these errors and standardize heart rate variability measuring, the European Society of Cardiology and the North American Society of Pacing and Electrophysiology have standardized measurement methods.

Obtain a printout of your electrocardiogram (ECG or EKG) test. The EKG, which records your heart rhythm, is a non-invasive procedure performed at a cardiologist's office. The results EKG are printed onto a type of graph paper as one continuous line with peaks and valleys. You'll need this information to calculate any heart rate variables.

Locate the QRS intervals from the EKG.The strongest heart beat you feel at the base of your wrist or on the side of your neck occurs when the heart ventricles contract. This contraction shows up on the EKG readout as a high spike in the line. The beginning of this spike is labeled with a Q. The peak of this spike is labeled with an R and the end of the spike with an S.

Circle the peaks, or Rs, of the spikes.

Count the number of small squares on the EKG paper between your first two circled Rs.

Divide 1,500 by the number of small squares. The result equals the number of contractions your heart makes in one minute.

Repeat steps 4 and 5 for the remaining Rs you have circled on your EKG printout.

Determine your heart rate variable. For example, if your first number is 104 and your next number is 120, your heart rate is varying by 16 contractions in a minute.