Blood Pressure Category Calculator

Enter a systolic (top) number of 128 and a diastolic (bottom) number of 76, both in mm Hg.

The calculator first places each number in its own category. A systolic of 128 is in the 120–129 range, which is Elevated. A diastolic of 76 is below 80, which on its own is Normal. The overall category is the higher of the two: Elevated, set by the systolic number.

It also shows the pulse pressure, the difference between the two numbers, which here is 52 mm Hg. Pulse pressure is not part of the guideline categories; it is shown because it is simple arithmetic on the numbers you already have.

Elevated is not hypertension, but it matters. The guideline treats it as a stage at which lifestyle changes are recommended, because blood pressure in that range tends to rise over time without them.

There is no formula here in the arithmetic sense. The calculator is a direct implementation of the category table in the 2017 ACC/AHA Guideline for the Prevention, Detection, Evaluation, and Management of High Blood Pressure in Adults (Whelton, Carey and colleagues, published in *Hypertension* and the *Journal of the American College of Cardiology* in 2018).

Systolic on its own: below 120 is Normal; 120 to 129 is Elevated; 130 to 139 is Stage 1; 140 or higher is Stage 2; above 180 is Hypertensive Crisis.

Diastolic on its own: below 80 is Normal; 80 to 89 is Stage 1; 90 or higher is Stage 2; above 120 is Hypertensive Crisis. There is no Elevated band for diastolic pressure — Elevated is defined by systolic pressure alone.

Combining them: the overall category is the more severe of the two individual categories. The crisis threshold uses 'and/or', so a systolic above 180 or a diastolic above 120 is enough on its own.

The boundaries are exact. 119/79 is Normal and 120/79 is Elevated. 129/79 is Elevated and 130/79 is Stage 1. 180/120 is Stage 2 and 181/85 is a Hypertensive Crisis reading. A 2025 update to the guideline from the AHA, the ACC and partner organisations kept these same categories.

Enter 128/84. The systolic number is the same as before and still Elevated on its own, but a diastolic of 84 falls in the 80–89 range. The overall category jumps to Stage 1 hypertension, and the calculator reports that the diastolic number set it. Pulse pressure is 44 mm Hg.

Now try 142/88. Here the systolic number is Stage 2 and the diastolic is Stage 1, so the reading is Stage 2, set by the systolic number.

Finally, 185/100. A systolic above 180 puts the reading in the Hypertensive Crisis range regardless of the diastolic number. The calculator shows a direct message: sit quietly, measure again after a few minutes, and if the reading is still above 180 or 120, contact a doctor promptly. If a reading in this range comes with chest pain, shortness of breath, back pain, numbness or weakness, a change in vision, or difficulty speaking, call emergency services immediately. Those symptoms can signal organ damage, and waiting to see whether the number comes down is the wrong response.

The lesson from all three is the 'higher category wins' rule. Looking only at the top number, which many people do, would have understated the second reading.

The category is only as good as the reading. The 2017 guideline sets out a measurement protocol, and home readings that skip it can be misleading in either direction:

• Avoid caffeine, exercise and smoking for at least 30 minutes beforehand, and empty your bladder.
• Sit for at least 5 minutes before measuring, with your back supported, feet flat on the floor and legs uncrossed.
• Rest your arm on a table so the cuff is at heart level, on bare skin, not over a sleeve.
• Use the right cuff size. The guideline advises a cuff whose inflatable bladder wraps around about 80% of the upper arm; a cuff that is too small reads high.
• Do not talk during the measurement. Take 2 or 3 readings a minute or so apart and record the average.

Home readings are valuable precisely because clinic readings can mislead. Some people read high only in a doctor's office (white-coat hypertension) and some read normal in the office but high at home (masked hypertension). The guideline recommends readings outside the clinic to confirm a diagnosis, based on the average of at least two readings on at least two occasions.

Not a diagnosis. This calculator categorises a reading. It cannot diagnose hypertension, which requires repeated readings and a clinical assessment.

Not a treatment guide. Whether treatment is recommended, especially in Stage 1, depends on overall cardiovascular risk, kidney disease, diabetes and other factors that a single category does not capture.

Adults only. Children and adolescents are assessed under separate pediatric guidance, the American Academy of Pediatrics' 2017 clinical practice guideline, not these adult cut-offs.

Not for pregnancy. Blood pressure in pregnancy is assessed against different criteria, and a raised reading in pregnancy should always be discussed promptly with a maternity care provider.

Device accuracy matters. Wrist and finger devices are generally less reliable than a validated upper-arm cuff. If your readings are unexpectedly high or low, check your device and technique with a clinician.

Blood pressure is one input to overall heart risk, not the whole of it. The Framingham cardiac risk calculator combines systolic pressure with age, cholesterol, smoking and diabetes into a 10-year cardiovascular risk estimate, which is the kind of number doctors weigh when deciding how to treat Stage 1 hypertension. Body weight is one of the strongest modifiable influences on blood pressure, so your BMI is worth knowing alongside it. And because high blood pressure often travels with metabolic problems, the HOMA insulin resistance calculator estimates insulin resistance from fasting glucose and insulin results.