Blood Pressure Home > Blood Pressure Readings

A reading for blood pressure consists of two blood pressure numbers. One represents the systolic blood pressure (while the heart is beating) and the other represents the diastolic blood pressure (while the heart is at rest). When readings are taken over a few days, your average blood pressure can be determined and you can know if you're in a healthy range.

What Are Blood Pressure Readings?

The two numbers that measure your blood pressure are written like a fraction: one number on top and one on the bottom (128/82). The number on top is called the systolic pressure. Systolic blood pressure measures the pressure inside your blood vessels at the moment your heart beats. The number on the bottom is your diastolic pressure. Diastolic blood pressure measures the pressure in your blood vessels between heartbeats, when your heart is resting.
Because your blood pressure changes so often throughout the day, it is better to use several readings to figure out your average blood pressure numbers. This is because, from day to day, a person's blood pressure usually fluctuates within a certain range. Things that can make a person's blood pressure change within a few minutes include:
  • Posture
  • Exercise
  • Tension
  • Tobacco use.
Blood pressure can also run high or low in families. Because of this, it's important to look at your overall health, lifestyle, diet, and family history when comparing your blood pressure readings to what's considered "normal."

What Is Considered Too High?

To find your average blood pressure reading, you will need to have readings taken two or more times, and each reading should be from a different day. Generally, anything under 120/80 is considered normal blood pressure, but extremely low blood pressure can also be a problem. Healthcare professionals consider average readings between 120/80 and 139/89 to be "prehypertension." If the average of your readings for blood pressure is more than 140 over 90, you have high blood pressure (hypertension).
A single reading of more than 140/90, however, doesn't necessarily mean that you have high blood pressure. But your doctor will likely want to watch your blood pressure over a certain period of time to see if it stays there. You can also have high blood pressure if the average of only one of the numbers in your readings is too high.
Written by/reviewed by:
Last reviewed by: Arthur Schoenstadt, MD
Last updated/reviewed:
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