Blood pressure is recorded with two numbers: the higher (systolic) value indicates the pressure during the heart’s contraction phase and the lower (diastolic) value indicates the pressure during the heart’s resting phase. For example, a blood pressure reading of 120/80 mmHg means that the systolic pressure is 120 mmHg and the diastolic pressure is 80 mmHg. The unit mmHg stands for millimeters of mercury.