How to Measure Your Blood Pressure Accurately

Measuring your blood pressure is the only way to know whether it is high. High blood pressure usually has no warning signs or symptoms, and many people who have it do not know. Regular checks help your health care team find problems early, and if your blood pressure is too high, you can take steps together to bring it under control. High blood pressure can also put a mother and baby at risk of problems during pregnancy.

Measuring at home

Ask your health care team about regularly measuring your blood pressure at home, known as self-measured blood pressure (SMBP) monitoring: using your own device away from the doctor's office or hospital. Home monitors are easy and safe to use, and a team member can show you how. Evidence shows that people with high blood pressure are more likely to lower it when they use SMBP together with support from their health care team.

• Record your readings in a blood pressure log.
• Measure at the same time every day.
• Take at least two readings, 1 or 2 minutes apart.

Ask your team how often to measure. People with high blood pressure may need to check more often than others, and anyone worried about their numbers should talk to their team about a plan. At any age, daily habits can help keep blood pressure in a healthy range.

How a professional measures it

A health care professional wraps an inflatable cuff around your arm and inflates it so that it gently tightens, then slowly lets the air out while listening to your pulse with a stethoscope — unless the cuff is digital or automatic, in which case no stethoscope is needed. It is quick and painless. The cuff's gauge measures the pressure in your blood vessels in millimeters of mercury (mm Hg).

You can have your blood pressure measured by a health care team member at a doctor's office, at a pharmacy with a digital measuring machine, or at home with your own monitor.

What can throw a reading off

• Nerves. Anxiety about having your blood pressure taken is called "white coat syndrome." As many as 1 in 3 people with a high reading at the doctor's office may have normal readings elsewhere.
• What you just did. Smoking, alcohol, caffeine or exercise within 30 minutes before a measurement can raise the reading.
• How you sit. Crossed legs, or an arm hanging at your side instead of resting on a table at chest height, can raise it.

Accuracy matters. A reading that is too low can give false reassurance, and one that is too high can lead to treatment you do not need.

Checklist for an accurate reading

CDC infographic: the correct way to measure blood pressure.

Whether at the doctor's office or at home:

• Don't eat or drink anything for 30 minutes beforehand.
• Empty your bladder first.
• Sit in a comfortable chair with your back supported for at least 5 minutes before the reading.
• Keep both feet flat on the floor and your legs uncrossed.
• Rest the arm with the cuff on a table at chest height.
• Make sure the cuff is snug but not too tight, and on bare skin rather than over clothing.
• Don't talk during the measurement.

Sources

• Centers for Disease Control and Prevention, "Measure Your Blood Pressure": https://www.cdc.gov/high-blood-pressure/measure/index.html