A normal blood pressure reading is below 120/80 mm Hg. That means a systolic (top number) under 120 and a diastolic (bottom number) under 80. Once either number crosses those thresholds, your blood pressure falls into a higher category, even if the other number stays in the normal range.
What the Two Numbers Mean
The top number, systolic pressure, measures the force your blood pushes against your artery walls each time your heart beats. The bottom number, diastolic pressure, measures that same force between beats, when the heart is resting. Both numbers matter, but they can tell different stories. A high systolic reading with a normal diastolic reading is common as arteries stiffen with age, while an elevated diastolic reading can signal problems with blood vessel resistance.
Blood Pressure Categories for Adults
The American Heart Association and American College of Cardiology classify adult blood pressure into four categories based on the 2025 guidelines:
- Normal: systolic below 120 and diastolic below 80
- Elevated: systolic 120 to 129 and diastolic below 80
- Stage 1 hypertension: systolic 130 to 139 or diastolic 80 to 89
- Stage 2 hypertension: systolic 140 or higher, or diastolic 90 or higher
If your systolic and diastolic numbers fall into two different categories, the higher category applies. So a reading of 135/75 counts as stage 1 hypertension because of the systolic number, even though the diastolic number is normal.
Why These Thresholds Matter
The cutoffs aren’t arbitrary. A large prospective study published in the Journal of the American Heart Association found that people with stage 1 hypertension had a 35% higher risk of cardiovascular disease over 10 years compared to those with normal blood pressure. The lifetime risk increase was similar, at 36%.
The bigger danger is progression. Among people who started at stage 1 and moved into stage 2, the 10-year cardiovascular risk jumped by 156%. That’s why catching elevated readings early matters so much. The gap between “a little high” and “too high” can close quickly, and the health consequences compound as it does.
When Blood Pressure Is Too Low
A reading below 90/60 mm Hg is generally considered low blood pressure. But unlike hypertension, low blood pressure is only a concern if it causes symptoms. Those symptoms include dizziness, blurred vision, fatigue, trouble concentrating, nausea, and fainting. A drop of just 20 mm Hg in systolic pressure, say from 110 to 90, can be enough to trigger lightheadedness.
Some people naturally run on the low side and feel perfectly fine. That’s not a problem. Extreme drops, however, can cause shock, marked by confusion, cold and clammy skin, rapid shallow breathing, and a weak pulse. That’s a medical emergency.
Blood Pressure in Children
The fixed thresholds above apply to adults. Children’s blood pressure is evaluated differently, using percentile charts based on age, sex, and height. A reading that’s normal for a 15-year-old may be high for a 7-year-old, and a taller child will naturally have slightly higher readings than a shorter child of the same age. Pediatricians compare a child’s reading against population data for kids of the same size and age, with the 90th percentile as the boundary where elevated readings begin.
Blood Pressure Goals for Older Adults
For adults over 50, the evidence supports keeping systolic pressure below 120. The SPRINT trial, a major NIH-funded study, found that hitting this lower target significantly reduced heart disease and death in adults 50 and older. That said, treatment decisions for older adults involve weighing other health conditions, medications, and overall fitness. Someone who is 80 and frail may have a different practical target than someone who is 65 and active.
How to Get an Accurate Reading
A single reading taken under the wrong conditions can easily be 10 to 20 points off. To get a reliable number, the National Heart, Lung, and Blood Institute recommends a specific routine:
- Avoid exercise, meals, caffeine, and smoking for at least 30 minutes before measuring.
- Empty your bladder first.
- Sit quietly for five minutes before taking the reading.
- Sit in a chair with your back supported and feet flat on the floor, uncrossed.
- Place the cuff on bare skin, above your elbow, at mid-arm height.
- Rest your arm on a table so the cuff sits at heart level, palm facing up.
- Don’t talk, watch TV, or look at your phone during the reading.
If you’re taking blood pressure medication, measure before your dose, not after. And take two readings about a minute apart, then average them. A single number from one visit isn’t enough to diagnose anything. Patterns over time are what matter.
What Can Temporarily Raise Your Reading
Caffeine can cause a short-term spike in blood pressure, particularly if you don’t drink it regularly. You can test your own sensitivity by checking your blood pressure about 30 minutes after a cup of coffee. If it climbs noticeably, caffeine is affecting your reading. Nicotine, a full bladder, stress, cold temperatures, and even talking during the measurement can all push your numbers up temporarily. This is why preparation matters so much. A “high” reading taken right after rushing to an appointment with a full bladder and a coffee in hand may not reflect your actual resting blood pressure at all.
Targets for People With Chronic Conditions
If you have diabetes or chronic kidney disease, the target is tighter than for the general population. Current guidelines recommend keeping blood pressure below 130/80 for people with these conditions, and some guidelines push even lower, recommending systolic pressure between 120 and 129. Research in the Journal of the American Heart Association confirmed that systolic pressure below 130 and diastolic below 80 reduced cardiovascular risk in people who had both diabetes and kidney disease. The higher your baseline risk, the more benefit you get from tighter control.