President Fords historic trip and fall down the steps of Air Force One. 1  People & Blogs. 2  Standard YouTube License.
The bottom number, called the diastolic pressure, is the measurement as the heart relaxes between beats. Normal blood pressure is a systolic pressure of less than 120 millimeters of mercury (mm Hg) and a diastolic pressure of less than 80 mm Hg, or 120/80 mm Hg, according to the American Heart Association (AHA). Having a blood pressure greater than 140/90 mm Hg is considered high blood pressure or hypertension. A blood pressure level between normal and hypertension, is called prehypertension, meaning it is higher than normal, but not high enough to be considered hypertension.
Note that blood pressure readings are expressed as millimeters of mercury. This unit is abbreviated as mm Hg. A normal reading would be any blood pressure below 120/80 mm Hg and above 90/60 mm Hg. Blood pressure that is too low does not supply your body and heart with enough oxygenated blood. Low blood pressure is known as hypotension.