Cardivo guides

Systolic vs. diastolic blood pressure: what the numbers mean

Updated October 17, 2026 · Wellness education, not medical advice

Key takeaways

Systolic = the top number: pressure in your arteries when your heart beats.
Diastolic = the bottom number: pressure when your heart rests between beats.
Normal: systolic below 120 and diastolic below 80 mm Hg.
Both matter. Either number being high is enough to be in a higher category.

What is blood pressure?

Blood pressure (BP) is the force of blood pushing against the walls of your arteries as your heart pumps. It's measured in millimeters of mercury (mm Hg) and written as two numbers, such as 117/76 — said "117 over 76".

Systolic vs. diastolic at a glance

	Systolic	Diastolic
Position	Top number	Bottom number
What it measures	Pressure when the heart contracts and pushes blood out	Pressure when the heart relaxes and refills between beats
Normal	Below 120 mm Hg	Below 80 mm Hg
Elevated	120–129	Below 80
Stage 1 hypertension	130–139	80–89
Stage 2 hypertension	140 or higher	90 or higher
Typical with age	Tends to rise as arteries stiffen	Often levels off or falls after midlife

What is systolic blood pressure?

Systolic pressure is the peak pressure in your arteries each time your heart squeezes. It's always the higher number. A normal systolic blood pressure is below 120 mm Hg. Systolic pressure tends to climb with age as large arteries become stiffer, and the AHA notes that the systolic number gets the most attention as a risk factor for heart disease in people over 50.

What is diastolic blood pressure?

Diastolic pressure is the lowest pressure in your arteries, between beats, while the heart refills. A normal diastolic blood pressure is below 80 mm Hg. A high diastolic number is especially common in younger adults with high blood pressure.

Which number is more important?

Both. High blood pressure is diagnosed if either number is high. In older adults, a high systolic number is the more common problem — called isolated systolic hypertension when only the top number is high. In younger adults, isolated diastolic hypertension can occur.

How to read your blood pressure numbers

Category	Systolic (top)		Diastolic (bottom)
Normal	Less than 120	and	Less than 80
Elevated	120–129	and	Less than 80
Stage 1 hypertension	130–139	or	80–89
Stage 2 hypertension	140 or higher	or	90 or higher
Severe — call 911 if symptoms	Higher than 180	and/or	Higher than 120

124/76 → elevated (top 120–129, bottom under 80)
118/84 → stage 1 (bottom 80–89)
142/88 → stage 2 (top 140+)

The difference between the two numbers is called pulse pressure (for 120/80, it's 40). Your doctor may look at it alongside your readings.

What about the pulse number?

Most home monitors show a third number: your pulse, or heart rate, in beats per minute. It isn't part of blood pressure, but it's worth logging too. A normal adult resting heart rate is about 60–100 bpm.

Track both numbers with Cardivo

Cardivo logs systolic, diastolic, and pulse from your cuff (or Apple Health), charts them over time, and shows heart rate and HRV from your iPhone camera alongside. Export a PDF for your doctor in one tap. Prefer paper? Use our free printable blood pressure log.

This guide is general wellness education based on the public sources below. It is not medical advice, diagnosis, or treatment. Cardivo is not a medical device. If you think you are having a medical emergency, call 911.

Frequently asked questions

What is the difference between systolic and diastolic blood pressure?

Systolic (top number) is the pressure in your arteries when your heart beats. Diastolic (bottom number) is the pressure when your heart rests between beats.

What is a normal systolic and diastolic blood pressure?

Normal is a systolic number below 120 and a diastolic number below 80 mm Hg.

Which is more important, systolic or diastolic?

Both matter, and either being high counts as high blood pressure. Systolic pressure becomes the more important risk factor for many people over 50.

Is high diastolic blood pressure dangerous?

A diastolic reading of 80–89 is stage 1 and 90 or higher is stage 2 hypertension. Over time it raises cardiovascular risk, so discuss repeated high readings with your doctor.

Sources

Cardivo is an ad-free iPhone app that reads heart rate and HRV from your fingertip on the camera in about 30 seconds — no Apple Watch needed — and keeps blood pressure, blood sugar, and mood in one journal you can share with your doctor as a PDF. Download on the App Store.