Nearly half of U.S. adults have high blood pressure, and many do not know it. Understanding your blood pressure readings is one of the simplest ways to keep track of heart, brain and kidney health. This guide explains what the two numbers mean, how the American Heart Association (AHA) categorizes blood pressure readings, how to measure at home accurately, and when a high number calls for a phone call versus a 911 call.
This article is general health information, not medical advice. Only a doctor or other qualified clinician can diagnose high blood pressure or recommend treatment.
What Do the Two Numbers Mean?
A reading such as 118/76 mm Hg (millimeters of mercury) has two parts, according to the American Heart Association:
- Systolic (top number): the pressure in your arteries when your heart beats.
- Diastolic (bottom number): the pressure in your arteries when your heart rests between beats.
The AHA notes that for people over 50, the systolic number is generally the stronger indicator of heart disease risk.
Blood Pressure Readings Chart: The Five Categories
These categories come from the AHA and American College of Cardiology (ACC). They were first set in 2017 and kept unchanged in the 2025 AHA/ACC high blood pressure guideline.
| 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 hypertension (called a hypertensive emergency if symptoms are present) | Higher than 180 | and/or | Higher than 120 |
All values in mm Hg. Source: American Heart Association.
Why “and” versus “or” matters
Notice the connecting words. To be “normal,” both numbers must be in range. For stage 1 or stage 2 hypertension, either number is enough. For example, a reading of 126/84 is stage 1 hypertension because the diastolic number is 80–89, even though the systolic number alone would only count as elevated.
One high reading is not a diagnosis
Blood pressure changes throughout the day with activity, stress, caffeine and even talking. Clinicians generally rely on several readings taken on different occasions, and the 2025 guideline encourages home monitoring to help confirm a diagnosis and guide treatment.
How Common Is High Blood Pressure?
Verified data from the Centers for Disease Control and Prevention (CDC):
- 48.1% of U.S. adults (about 119.9 million people) have high blood pressure, defined as 130/80 mm Hg or higher or taking medication for it.
- Only about 1 in 4 adults with high blood pressure (22.5%) has it under control.
- About 1 in 6 adults with high blood pressure does not know they have it.
- In 2024, high blood pressure was a primary or contributing cause of 680,179 U.S. deaths.
Because high blood pressure usually causes no symptoms, regular checks are the main way to find it. Over time, uncontrolled hypertension raises the risk of heart attack, stroke, heart failure and kidney disease. For more on the heart-failure link, see our report on heart failure statistics for 2026.
How to Take Accurate Blood Pressure Readings at Home
Technique matters as much as the device. The AHA’s home monitoring guidance recommends:
- Use the right device. Choose an automatic, upper-arm cuff that has been validated for accuracy (the AHA points to validatebp.org) and fits your arm. Wrist and finger monitors are not recommended.
- Prepare. Avoid smoking, caffeine and exercise for at least 30 minutes beforehand, and empty your bladder.
- Rest first. Sit quietly for at least five minutes without talking or looking at your phone.
- Position yourself correctly. Sit with your back supported and your arm resting on a flat surface at heart level. Place the cuff on bare skin, with the bottom edge just above the bend of the elbow.
- Take two readings, one minute apart, at the same time each day or as your clinician advises.
- Record everything. Keep a log or use the monitor’s memory, and bring the results to appointments. Have your clinician check your technique and compare your monitor with office equipment about once a year.
When Is a High Reading an Emergency?
The AHA separates very high readings into two situations:
- Above 180/120 with no symptoms: Wait one minute and measure again. If it is still that high, contact your healthcare professional right away.
- Above 180/120 with symptoms: Call 911. Warning signs include chest pain, shortness of breath, back pain, numbness, weakness, vision changes, or difficulty speaking.
The AHA also advises never stopping blood pressure medication without talking to your clinician, whatever your home readings show.
What the 2025 Guideline Says About Lowering Blood Pressure
Summary of the August 2025 AHA/ACC guideline, as reported by Patient Care. Treatment decisions belong to patients and their clinicians.
- Treatment goal: For most adults being treated, the recommended target is below 130/80 mm Hg.
- Lifestyle comes first: Eat a DASH-style diet, keep sodium under 2,300 mg a day (ideally toward 1,500 mg), limit alcohol, stay physically active, manage stress, and lose at least 5% of body weight if you have overweight or obesity.
- Risk-based decisions: Clinicians are encouraged to use the AHA’s PREVENT calculator to estimate 10- and 30-year cardiovascular risk for adults ages 30 to 79.
- Medication when needed: For stage 2 hypertension, the guideline recommends starting with two medications, preferably combined in a single pill.
Frequently Asked Questions About Blood Pressure Readings
Is 120/80 a normal blood pressure?
Under AHA categories, normal is less than 120/80. A systolic reading of 120 with a diastolic under 80 falls in the “elevated” range, and a diastolic of exactly 80 falls in stage 1.
Which number is more important?
Both matter, and either can place you in a hypertension category. The AHA notes that systolic pressure is generally a stronger predictor of heart disease risk after age 50.
Why is my reading higher at the doctor’s office?
Some people’s readings rise in clinical settings, which is one reason home monitoring is used to confirm a diagnosis. Share your home log with your clinician.
Do I need to fast before checking my blood pressure?
No fasting is needed for a blood pressure check, but avoid caffeine, smoking and exercise for 30 minutes beforehand. For lab tests, see our explainer on fasting before a blood test.
Related Health Coverage on Vanderbiltreport.com
- Heart Failure Statistics 2026: Deaths Are Rising and Younger Adults Are Increasingly Affected
- Gut Microbe and Heart Disease: Nature Study Finds Bacterium That Shrinks Artery Plaque
- Fasting Before a Blood Test: What a Study of 9.7 Million Results Found
- More General Health articles
Sources
- American Heart Association — Understanding Blood Pressure Readings
- American Heart Association — Monitoring Your Blood Pressure at Home
- CDC — High Blood Pressure Facts
- Patient Care — AHA/ACC release revised hypertension guidelines (Aug. 2025)
- ValidateBP.org — Validated blood pressure devices
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