Blood Pressure Numbers
There are two kinds of numbers that make up a blood pressure reading. These numbers are written like a fraction -- the top number refers to systolic blood pressure (while the heart is beating), and the bottom number measures the diastolic blood pressure (while the heart is at rest). Normal numbers for blood pressure range from 90/60 to 120/80.
What Do Blood Pressure Numbers Mean?
The two numbers that measure your blood pressure are written like a fraction: one number on top and one on the bottom -- for example, 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 best to use more than one reading to figure out your average blood pressure. This is because, from day to day, a person's blood pressure usually fluctuates within a certain range. Posture, exercise, tension, and nicotine use are a few things that can make a person's blood pressure change within a few minutes. Blood pressure can also run high or low in families. When comparing your blood pressure numbers to what's considered "normal," it's important to look at your:
- Family history
- Overall health
What's Too High?
To find your average blood pressure, you will need to have your blood pressure taken two or more times, and each reading should be from a different day. Anything under 120/80 is considered normal blood pressure, but very low blood pressure can also be a health concern. Average numbers for blood pressure between 120/80 and 139/89 are considered to indicate "prehypertension." If the average of your blood pressure numbers is more than 140/90, you have high blood pressure.
One reading of more than 140/90, however, doesn't necessarily mean that you have high blood pressure. Although it's likely that your doctor will 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.