Reading your blood pressure number properly
Blood pressure is recorded as two numbers — systolic over diastolic — and both carry independent clinical significance. This calculator applies the American Heart Association's category thresholds, the most widely referenced framework for interpreting a blood pressure reading.
Normal blood pressure sits below 120/80 mmHg. Elevated readings (120-129 systolic, under 80 diastolic) suggest a trend worth monitoring without yet meeting the threshold for hypertension. Stage 1 and Stage 2 hypertension reflect progressively higher sustained risk, while a hypertensive crisis reading (180/120 or higher) warrants prompt medical attention.
Why a single reading isn't the full picture
Blood pressure fluctuates throughout the day in response to activity, stress, caffeine, and even the simple anxiety of having it measured — a well-documented phenomenon sometimes called "white coat syndrome." This is why clinical hypertension diagnoses typically require multiple elevated readings across different occasions, rather than relying on any single measurement.
Measuring at home accurately
For the most reliable home readings: sit quietly for five minutes beforehand, keep your arm supported at heart level, avoid caffeine or exercise in the prior 30 minutes, and take two or three readings a minute apart, using the average. Consistency in technique matters more than any single reading's exact number.