Diastolic Blood Pressure

Measured in mmHg

The bottom blood pressure number — the pressure in your arteries between heartbeats — which, like the top number, varies enough that one reading tells you little.

What it is

Diastolic blood pressure is the bottom number in a reading, reflecting the pressure remaining in your arteries while your heart relaxes and refills between beats. It measures something different from the systolic (top) number, and the two don't always move together, so clinicians look at both alongside your broader health context. Like systolic, it shifts with stress, time of day, cuff fit, arm position, and the 'white coat' effect, so it can be associated with meaning only when viewed across repeated measurements. A single diastolic value — especially one taken in an unfamiliar setting — is a weak estimate of your typical pressure.

Typical range

  • Adultsunder 80 mmHg

Source · 2025 AHA/ACC (2025)

Reference ranges vary between laboratories, and what is normal for you depends on your own history. Your own lab’s range is the one printed on your report.

Worth asking your clinician

  • What does my diastolic number add to the picture beyond my systolic number?
  • Is the gap between my top and bottom numbers something you find meaningful for me?
  • How many readings, and over what period, would you want before drawing any conclusion from my diastolic trend?