Calculators > Heart Health

Blood Pressure Calculator

Calculate blood pressure measurement category, to find out if blood pressure is normal, elevated, or high blood pressure Stage 1 or 2.

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Related: Blood Pressure Average Calculator, Blood Pressure Tracker

What is Blood Pressure?

Blood moves throughout the body via its network of arteries and veins. Arteries move oxygen rich blood from the heart to other parts of our body, including cells and organs; Veins return deoxygenated blood back to the heart.

Blood pressure (BP) is a measurement of the force of blood within the arteries each time the heartbeats, indicating how hard the heart is having to work. When blood pressure is above the normal level, it indicates the heart is having to work harder in order to pump blood.

What is Systolic Pressure and Diastolic Pressure?

A blood pressure measurement is comprised of two numbers: Systolic Pressure and Diastolic Pressure. A blood pressure reading is represented as Systolic/Diastolic. For example, in 120/75, systolic is 120 and diastolic is 75.

Systolic Pressure

Systolic Pressure is the pressure exerted on the artery walls when the heartbeats.

Systolic is the top number in your blood pressure reading. In 126/82, systolic is 126.

Diastolic Pressure

Diastolic Pressure is the arterial pressure between beats. It is the resting phase before the next heartbeat.

Diastolic is the bottom number in your blood pressure reading. In 126/82, diastolic is 82.

What is mm Hg?

Blood pressure is measured in millimeters (mm) of mercury (Hg). The chemical symbol for mercury is Hg.

Blood pressure monitors were invented at the end of the 19th century. Called a sphygmomanometer, it went through several changes in the early 20th century, arriving at the version still used in many doctor's offices, with an inflatable cuff and a manometer. Digital sphygmomanometer, more simply called blood pressure monitors, were invented in the early 1970s, ultimately enabling home blood pressure monitoring.

Find out more about sphygmomanometers at Encyclopedia Britannica.

What are the Blood Pressure Categories?

In 2017, the American College of Cardiology (ACC) and the American Heart Association (AHA), in conjunction with several other professional health orgranizations, updated the guidelines for categorizing blood pressure readings, the first such major revision since 2003.

A significant change to the AHA/ACC guidelines is that it lowers the numbers defining high blood pressure, enabling earlier awareness and intervention, if necessary.

According to the ACC/AHA Guidelines, there are 5 blood pressure categories:

  • Normal

  • Elevated

  • High Blood Pressure (Hypertension) Stage 1

  • High Blood Pressure (Hypertension) Stage 2

  • Hypertensive Crisis - As per ACC/AHA guidelines, consult medical doctor immediately. Defined as higher than 180/120: Systolic above 180 and/or Diastolic above 120.

Important: This calculator is limited to blood pressure readings that fall within the categories Normal, Elevated, Hypertension Stage 1 and Stage 2. That is, BP readings in the range 91/61 to 180/120. Contact a qualified medical doctor if your numbers are outside these ranges.

What is Hypertension?

Hypertension is the medical term for high blood pressure. High blood pressure is when the force of blood moving through the arteries is greater than what is considered normal.

According to the ACC/AHA 2017 revised guidelines:

  • Stage 1 high blood pressure (hypertension) is defined as Systolic 130-139 or Diastolic 80-89.

  • Stage 2 high blood pressure is defined as Systolic 140-179 or Diastolic 90-119.

  • Hypertensive Crisis is Systolic higher than 180, and/or Diastolic higher than 120. For Hypertensive Crisis, ACC/AHA guidelines indicate to consult your doctor immediately.

According to the U.S. Centers for Disease Control and Prevention (CDC), high blood pressure often has no signs or symptoms and consequently many people are unaware that they are afflicted with it. For this reason, it is often called the silent killer, since, left untreated, hypertension can lead to several life threatening diseases, including stroke and heart disease.

Measuring blood pressure is a simple test which can determine if you have high blood pressure. It can be done in a doctor's office, or at home with a monitor. More information on blood pressure tests at Mayo Clinic .

For information on the impact of high blood pressure, see High Blood Pressure Facts at cdc.gov

For information on the harmful effects of high blood pressure, see High Blood Pressure Dangers, at the Mayo Clinic

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