Blood Pressure Category Calculator

A blood pressure reading is two numbers. The top number, systolic, is the peak pressure in your arteries as the heart contracts. The bottom number, diastolic, is the pressure that remains between beats as the heart relaxes. Both are measured in millimetres of mercury and written as 120/80 mmHg.

This calculator sorts a single reading into the categories published by the American Heart Association. Normal is below 120 over 80. Elevated is a systolic of 120 to 129 with a diastolic still under 80. Stage 1 hypertension is 130 to 139 systolic or 80 to 89 diastolic. Stage 2 is 140 or higher systolic, or 90 or higher diastolic. A reading above 180 over 120 is classed as a hypertensive crisis and calls for prompt medical attention rather than a website.

Two derived numbers add context. Mean arterial pressure, roughly the average pressure driving blood through the body, is calculated as systolic plus twice diastolic, divided by three; it weights the diastolic phase more heavily because the heart spends about two-thirds of each cycle relaxing. Pulse pressure, the gap between the two numbers, tends to widen with age as arteries stiffen, and a persistently wide pulse pressure is worth mentioning to a clinician.

Single readings are noisy. Blood pressure swings with stress, caffeine, the time of day, whether you have just walked upstairs, and even the act of having it taken. A diagnosis is never made from one measurement. If a casual reading here is high, rest for five minutes, sit with your back supported and your arm at heart level, and measure again. If it stays high across several days, see a doctor. This tool is for information only and is not a diagnosis or a substitute for professional medical advice.

This calculator returns estimates for general information only. It is not medical advice, diagnosis or treatment, and it cannot replace an assessment by a qualified health professional. Individual results vary, and figures such as calorie needs, body-fat percentage and heart-rate zones are approximations based on population averages rather than measurements of you.