A heart rate is obtained by feeling for the pulse at one of the body's pressure points and tracking the number of beats for a set period of time, according to the American Heart Association. The goal is to determine the number of beats in one minute.
The pulse can be felt at several points on the body. For healthy adults and patients with a diastolic blood pressure above 80 mm Hg, the pulse is most often taken at the wrist. If the pulse is not present at the wrist or the patient is under the age of 5, the pulse may be taken at the brachial artery in the upper arm. The pulse can also be felt along the carotid artery in the neck and the popliteal region behind the knee. Once a pulse is found, the heart rate can be calculated in beats per minute by counting the number of beats in a 10-second period and multiplying the result by six, according to the American Heart Association. This gives a per-minute figure with an acceptable accuracy for most purposes. For a more precise reading, it is possible to count for 30 seconds and multiply by two. For an exact reading, it is possible to hold and count for an entire minute.