INFOGRAPHIC

What Is Diastolic Blood Pressure?

By Amanda Doyle
Reviewed by Claudia Levi, R.N.
June 20, 2025
diastolic blood pressure noun The second number in a blood pressure reading. It’s a measure of pressure against the artery walls as the heart rests between beats.

A blood pressure reading consists of two numbers. The first is systolic blood pressure, and the second is diastolic blood pressure. Diastolic blood pressure measures the pressure of your blood against the artery walls while your heart rests between beats.

Blood pressure is measured in units called millimeters of mercury (mm Hg). A doctor may diagnose high blood pressure (hypertension) when diastolic blood pressure is between 80-89 mm Hg or higher. A normal diastolic blood pressure is less than 80 mm Hg.