Normal blood pressure for adults is a reading below 120/80 mm Hg. That means the top number (systolic) stays under 120 and the bottom number (diastolic) stays under 80. These thresholds were reaffirmed in the 2025 guidelines issued jointly by the American Heart Association, American College of Cardiology, and more than a dozen other medical organizations.
A blood pressure reading gives you two numbers, and both matter. Understanding what they mean, where the cutoffs fall, and what can throw off a reading puts you in a much better position to interpret your own results.
What the Two Numbers Mean
The top number, systolic pressure, measures the force your blood pushes against artery walls each time your heart beats and pumps blood out. The bottom number, diastolic pressure, measures that same force between beats, while your heart relaxes and refills with blood. Both are recorded in millimeters of mercury (mm Hg), a unit carried over from the original mercury gauges used to measure pressure.
A reading of 115/75, for example, means your arteries experience 115 mm Hg of pressure during each heartbeat and 75 mm Hg of pressure between beats. The higher the numbers climb, the harder your heart and blood vessels are working.
Blood Pressure Categories for Adults
Current guidelines break adult blood pressure into four categories based on office (clinical) readings:
- Normal: systolic below 120 and diastolic below 80
- Elevated: systolic 120 to 129 and diastolic still 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 is the one that applies. So a reading of 135/72 counts as stage 1 hypertension even though the bottom number looks fine.
When Blood Pressure Is Too Low
A reading below 90/60 mm Hg is generally considered low blood pressure, or hypotension. Not everyone with numbers in that range feels symptoms, but a sudden drop of just 20 points in systolic pressure can cause dizziness or fainting. If your blood pressure is consistently low and you feel fine, it usually isn’t a concern. Symptoms like lightheadedness, blurred vision, or fatigue are what signal a problem.
Blood Pressure in Children
The adult cutoff of 120/80 does not apply to kids. Normal blood pressure in children depends on age, sex, and height, and it rises gradually as they grow. A one-year-old boy, for instance, typically has a systolic pressure around 80 to 89 mm Hg and a diastolic pressure around 34 to 39 mm Hg. A one-year-old girl runs slightly higher on the systolic side, around 83 to 90. By the late teen years, children’s numbers begin approaching adult ranges. Pediatricians use percentile charts that account for all three variables to determine whether a child’s reading is normal.
Blood Pressure in Older Adults
Arteries stiffen with age, so systolic pressure tends to creep upward over the decades. For adults over 65, the right blood pressure target depends on overall health, fitness level, and other conditions like diabetes or kidney disease. There is no single universal goal for this age group. Treatment decisions typically involve weighing the benefits of lowering pressure against the risk of side effects like dizziness or falls, which hit older adults harder.
What Can Throw Off a Reading
Blood pressure is not a fixed number. It shifts throughout the day and reacts to dozens of short-term influences. Drinking caffeine or alcohol, smoking, or exercising within 30 minutes of a reading can push your numbers higher. So can something as simple as crossing your legs or letting your arm hang at your side instead of resting it on a table at chest height.
Stress plays a major role too. “White coat syndrome,” the spike in blood pressure caused by the anxiety of being in a medical setting, affects as many as 1 in 3 people whose readings come back high at the doctor’s office. These same people may have perfectly normal readings at home. The reverse also happens: some people read normal in the clinic but run high the rest of the time, a pattern called masked hypertension.
How to Get an Accurate Reading
Small details in how blood pressure is measured make a surprising difference in accuracy. The American Heart Association recommends sitting quietly for three to five minutes before a reading, without talking or moving around. Your arm should rest on a flat surface like a desk, with the middle of the cuff at heart level. If the cuff sits too low, the reading will come out artificially high.
Cuff size matters more than most people realize. A cuff that’s too small inflates the numbers; one that’s too large gives a falsely low result. The bladder inside the cuff should wrap around 75 to 100 percent of your upper arm. If you’re buying a home monitor, measure your arm circumference first and match it to the cuff sizing chart on the box.
Home Readings vs. Clinic Readings
If you monitor at home, your numbers may look slightly different from what you see at the doctor’s office, and the thresholds shift accordingly. For diagnosing hypertension, a home reading of 130/80 is considered equivalent to the same 130/80 clinic threshold at the stage 1 level. At higher levels the gap widens: a clinic reading of 140/90 corresponds roughly to a home reading of 135/85, and a clinic reading of 160/100 lines up with about 145/90 at home.
Because white coat syndrome and masked hypertension are both common, many doctors now recommend confirming an office reading with home monitoring over several days. A single high reading in a clinic doesn’t necessarily mean you have hypertension, and a single normal reading doesn’t guarantee you’re in the clear.