Normal Blood Pressure
Many people define normal blood pressure as an average reading of 120/80 or below. An average blood pressure can only be determined when multiple readings are taken over at least three days. Several things (such as lifestyle and family history) can affect a person's blood pressure range. Be mindful of this when comparing your reading to what's considered "normal blood pressure."
What Is a Normal Blood Pressure?
Blood pressure is the amount of force (pressure) that blood exerts on the walls of the blood vessels as it passes through them. Most healthcare providers agree that healthy blood pressure can fall anywhere within the normal blood pressure range. However, blood pressure can also be too high or too low -- both of which can cause problems.
Measuring Blood Pressure
To measure your blood pressure, a fabric cuff is wrapped around your arm and then slightly inflated. The blood pressure is measured by a gauge attached to the cuff. Your healthcare provider reads the numbers from the gauge as air is released from the cuff. The device that reads blood pressure is called a sphygmomanometer. Blood pressure can also be measured with a special machine.
The two numbers that measure your blood pressure are written like a fraction: one number on top and one on the bottom. Healthcare providers consider a normal blood pressure reading to be 120/80 or below. However, it can actually fall anywhere in a range from 90/60 to 120/80 -- it's not just one set number.
The number on top of the reading is called the systolic pressure. It measures the pressure inside your blood vessels at the moment your heart beats. The number on the bottom is your diastolic pressure. It measures the pressure in your blood vessels between heartbeats, when your heart is resting.
Factors Affecting "Normal" Blood Pressure
Blood pressure changes frequently throughout the day. Things that can make it change within a few minutes include:
- Amount of tension
- Level of exercise
- Nicotine use.
It's easy to see why even normal blood pressure can fluctuate within a certain range every day. Given these expected fluctuations, it's best to use more than one blood pressure reading to figure out your normal blood pressure.
Blood pressure can also run high or low in families. Therefore, it's important to look at your overall health, lifestyle, diet, and family history when comparing your blood pressure to what's considered "normal blood pressure." These factors may cause you to have a higher or lower reading than what's considered normal.
(Click Blood Pressure Numbers to see what are considered high or normal blood pressure readings.)