A healthy blood pressure reading for adults is less than 120/80 mm Hg. That first number (systolic) measures the pressure in your arteries when your heart beats, and the second number (diastolic) measures the pressure between beats. Once either number rises above those thresholds, your cardiovascular risk starts climbing, even if you feel perfectly fine.
Blood Pressure Categories for Adults
The American Heart Association breaks adult blood pressure into five categories based on where your numbers fall:
- Normal: Below 120 systolic and below 80 diastolic
- Elevated: 120 to 129 systolic with diastolic still below 80
- Stage 1 hypertension: 130 to 139 systolic, or 80 to 89 diastolic
- Stage 2 hypertension: 140 or higher systolic, or 90 or higher diastolic
- Hypertensive crisis: Higher than 180 systolic and/or higher than 120 diastolic
Notice that only one number needs to be high for you to land in a higher category. If your systolic is 142 but your diastolic is 78, that still counts as Stage 2 hypertension. The “elevated” category is unique because it only applies when systolic is creeping up while diastolic stays normal, which is often the earliest warning sign that your blood pressure is trending in the wrong direction.
What the Two Numbers Tell You
Systolic pressure (the top number) is the stronger predictor of cardiovascular events like heart attack and stroke at any age. But the bottom number matters too, especially if you’re younger. Research involving large populations found that for people under 50, diastolic readings provided additional predictive information about future heart disease risk. In practical terms, a 35-year-old with a diastolic of 92 should take that seriously, even if the top number looks reasonable.
As you get older, systolic pressure tends to rise because large arteries stiffen, plaque builds up, and rates of heart and blood vessel disease increase. This is why doctors pay particular attention to that top number in people over 50. A systolic reading of 150 in a 70-year-old carries real risk, regardless of what the diastolic reads.
Blood Pressure in Children and Teens
Children’s blood pressure is not measured against the same fixed numbers that adults use. Instead, a child’s reading is compared to what’s normal for their age, sex, and height. A healthy reading falls below the 90th percentile for kids with similar body size. Above the 95th percentile is considered hypertension.
To give you a sense of scale: a 17-year-old boy of average height typically has a blood pressure around 118/67. That same boy would cross into the hypertension range at roughly 136/87. For a 17-year-old girl of average height, a typical reading is about 111/66, with the hypertension threshold near 129/84. These numbers shift year by year through childhood, so your pediatrician uses age-specific charts rather than a single cutoff.
When Blood Pressure Is Too Low
A reading below 90/60 mm Hg is generally considered low blood pressure. But unlike high blood pressure, low readings are only a concern when they cause symptoms. Some people walk around at 88/58 and feel great. Others experience blurred vision, dizziness, lightheadedness, fatigue, or trouble concentrating.
Sudden drops are the real danger. A fall of just 20 mm Hg, say from standing up too quickly, can make you dizzy or faint. Extremely low blood pressure can lead to shock, which shows up as confusion (especially in older adults), cold and clammy skin, rapid shallow breathing, and a weak pulse. That’s a medical emergency.
When Numbers Become an Emergency
A reading of 180/120 or higher is a hypertensive crisis. What happens next depends on whether your organs are being damaged. If you have symptoms like chest pain, severe headache, vision changes, or shortness of breath alongside those numbers, that’s a hypertensive emergency, and you need to call 911 immediately. Organ damage to the heart, brain, kidneys, or eyes can happen rapidly at those pressures.
If your blood pressure hits 180/120 but you have no symptoms, rest quietly for a few minutes and measure again. If it stays that high, seek medical attention that day. Even without symptoms, sustained pressure at that level causes damage you can’t feel.
Getting an Accurate Reading
Your numbers are only useful if you’re measuring correctly, and small mistakes can swing a reading by 10 to 20 points. The CDC recommends sitting in a comfortable chair with your back supported for at least five minutes before taking a reading. Rest your arm on a table at chest height, with the cuff against bare skin (not over a sleeve). The cuff should be snug but not tight.
Crossing your legs, talking during the reading, using a cuff that’s too small for your arm, or skipping that five-minute rest period can all inflate your numbers artificially. If you only check your blood pressure at the doctor’s office, you may also be dealing with the “white coat effect,” where the anxiety of a medical visit pushes your reading higher than your actual baseline. A clinically significant white coat effect is defined as office readings that exceed your daytime home average by 20 mm Hg systolic or 10 mm Hg diastolic. If your numbers are borderline at the clinic, tracking at home with a validated monitor gives you a much clearer picture.
Take two or three readings a minute apart and average them. Single readings can be misleading. And measure at roughly the same time each day, since blood pressure fluctuates naturally throughout the day, running lower in the morning and peaking in the late afternoon.