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Measuring Blood Pressure

A man getting his blood pressure taken.

Measure your blood pressure regularly. It is quick and painless, and it is the only way to know whether your pressure is high. You can check your blood pressure at a doctor's office, at a pharmacy, or at home.

How Blood Pressure is Measured

First, a doctor or other health professional wraps a special cuff around your arm. The cuff has a gauge on it that will read your blood pressure. The doctor then inflates the cuff to squeeze your arm.

After the cuff is inflated, the doctor will slowly let air out. While doing this, he or she will listen to your pulse with a stethoscope and watch the gauge. The gauge uses a scale called "millimeters of mercury” (mmHg) to measure the pressure  measures blood pressure in your blood vessels.

Another option is to get a blood pressure measurement from the machines available at many pharmacies. There are also home monitoring devices for blood pressure that you can use yourself. Learn more about self-measured blood pressure monitoring [PDF-1M].

What Blood Pressure Numbers Mean

Blood pressure is measured using two numbers. The first number, called systolic blood pressure, measures the pressure in your blood vessels when your heart beats. The second number, called diastolic blood pressure, measures the pressure in your blood vessels when your heart rests between beats.

If the measurement reads 120 systolic and 80 diastolic, you would say "120 over 80" or write "120/80 mmHg."

The chart below shows normal, at-risk, and high blood pressure levels. A blood pressure less than 120/80 mmHg is normal. A blood pressure of 140/90 mmHg or more is too high. People with levels in between 120/80 and 140/90 have a condition called prehypertension, which means they are at high risk for high blood pressure.

Blood Pressure Levels

Normal

systolic: less than 120 mmHg
diastolic: less than 80mmHg

At risk (prehypertension)

systolic: 120–139 mmHg
diastolic: 80–89 mmHg

High

systolic: 140 mmHg or higher
diastolic: 90 mmHg or higher


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