It is usually expressed as the systolic over the diastolic pressure in units of mm of mercury (Hg). For a young healthy adult the blood pressure would be approximately 120/80 mm Hg.

Mean blood pressure and pulse pressure may also be calculated.

Additional Information

Mean Blood Pressure
This is the average pressure throughout the cardiac cycle and can only be determined by integrating the area of the pressure curve.

However it may be approximated from the following equations:

(systolic pressure + (2 x diastolic pressure)) / 3

Thus for a young healthy adult (BP = 120/80 mm Hg) the mean blood pressure would be (120 + 160) / 3 = 93 mm Hg.

or from diastolic pressure + (pulse pressure/3)

e.g. 80 + 13.3 = 93 mm Hg

Pulse Pressure
This is the difference between systolic and diastolic pressure.
e.g. If blood pressure = 120/80 mm Hg then:
pulse pressure = 120 – 80 = 40 mm Hg.