Your Blood Pressure Reading

What do the numbers mean in a blood pressure reading?

  • The unit used to measure blood pressure is the element mercury. According to the American Heart Association, mercury has long been used to gauge pressure and is still the preferred measurement of pressure in many medical tests.
  • The top number is the systolic blood pressure measurement, which measures the amount of pressure exerted by the blood against artery walls when the heart beats.
  • The bottom number is the diastolic blood pressure measurement, which measures the amount of pressure exerted by the blood against the artery walls between heat beats.

Blood pressure measurements are most effective when the patient is relaxed. Stress, physical exertion, and other factors can temporarily increase blood pressure. It is important to monitor blood pressure over time when you are at ease and resting to get the most accurate understanding of your blood pressure.

SOURCE: American Heart Association, “Know Your Numbers: Understanding Blood Pressure Readings”.

SOURCE: Blood Pressure UK

The American Heart Association designates certain ranges that help determine the most effective way to reduce blood pressure.

Severity Name Range Treatments
No severity Normal <120/<80 mm Hg No treatment required
Low severity Elevated 120-129/<80 mm Hg Lifestyle changes
Moderate severity Hypertension Stage 1 130-129/80-89 mm Hg Lifestyle changes and medication
High severity Hypertension Stage 2 >140/>90 mm Hg Lifestyle changes and combination of medication
Critical severity Hypertensive crisis 180/120 mm Hg Immediate medical attention


Blood pressure changes and varies often based on several different factors. Usually one reading is not enough to determine if someone has hypertension. Making a habit of checking and tracking your blood pressure will be useful in determining whether or not you truly are at risk. Taking steps to prevent high blood pressure, however, are a good idea for everyone.