which number is the systolic
Blood pressure is measured using two numbers. The first number, called systolic blood pressure, measures the pressure in your blood vessels when your heart beats. The second number, called diastolic blood pressure, measures the pressure in your blood vessels when your heart rests between beats. If the measurement reads 120 systolic and 80 diastolic, you would say 120 over 80 or write 120/80 mmHg.. The chart below shows normal, at-risk, and high blood pressure levels.