According to Blood Pressure UK, an ideal adult blood pressure reading is one that is below 120 over 80. At or below this level, the risk for stroke or heart disease is low.
The American Heart Association explains that the first number indicates the pressure in the arteries when the heart beats, and the second number shows the pressure when the heart is at rest. Blood pressure is measured in units of millimeters of mercury (mm Hg). In the majority of people, blood pressure rises with age. Factors such as level of stress and physical activity may also lead to higher or lower blood pressure readings.