Normal blood pressure for an adult is below 120 systolic and 80 diastolic. The normal range is lower for children and teenagers, states Mayo Clinic.
Systolic blood pressure, the top number in a blood pressure reading, measures the pressure on the arteries as the heart pumps blood through the body, states WebMD. The bottom number, or diastolic pressure, measures the arterial pressure between heartbeats.
Healthy diet and exercise contribute to maintaining a normal blood pressure, states Mayo Clinic. When blood pressure remains in a healthy range, the chances of heart attack, stroke and arterial disease lower. Due to these risks, high blood pressure, or hypertension, is often referred to as a silent killer, according to WebMD.