Blood pressure is the force of the blood against the walls of the arteries. It is measured by a ratio of two numbers:

Systolic – registered during a heartbeat (when the heart muscle contracts)

Diastolic – registered between heartbeats (when the heart rests and refills with blood)

Blood pressure is measured in a numerical reading of millimeter of mercury, abbreviated as mm Hg. Optimal blood pressure is less than 120/80 mm Hg. In general, the lower your blood pressure is, the better.

120–139 / 80–89 is considered prehypertension

140/90 or higher is hypertension, or high blood pressure. This puts a person at a greater risk for heart attack, angina, stroke, kidney failure and peripheral artery disease.