mmHg in a blood pressure (BP) reading stands for millimeters of mercury, which is the unit of measurement used to express blood pressure.
Understanding mmHg and Blood Pressure
Blood pressure is the force of your blood pushing against the walls of your arteries. It is measured in two numbers:
- Systolic pressure: The pressure when your heart beats (when the heart muscle contracts).
- Diastolic pressure: The pressure when your heart rests between beats (when the heart muscle relaxes).
These two pressures are written as one number over the other, for example, 120/80 mmHg. The "mmHg" indicates that the pressure is being measured in millimeters of mercury.
Why Millimeters of Mercury?
Historically, blood pressure was measured using a mercury manometer. The height of the mercury column that the blood pressure could push up was then measured in millimeters. Although digital blood pressure monitors are now common, the unit of measurement (mmHg) has remained.
Example
If your blood pressure reading is 130/85 mmHg, this means:
- Your systolic blood pressure is 130 mmHg.
- Your diastolic blood pressure is 85 mmHg.
