How to interpret a blood-pressure reading
Blood pressure is written as two numbers in millimeters of mercury (mm Hg). Systolic pressure is the top number, measured as the heart beats; diastolic pressure is the bottom number, measured between beats. This checker compares the numbers you enter with general adult categories, but it cannot diagnose hypertension from one measurement.
A reading needs context
Rest quietly and use a correctly sized cuff according to the monitor instructions. A single unusual reading can happen; the American Heart Association advises taking a second measurement when a reading is higher than normal and keeping a record over time. Its home-monitoring guidance explains the categories and when to contact a professional.
If a reading is higher than 180 systolic and/or 120 diastolic, wait at least one minute and measure again. If it remains that high, contact a healthcare professional immediately. If the very high reading occurs with symptoms such as chest pain, shortness of breath, weakness, vision changes, or difficulty speaking, call emergency services. Blood-pressure interpretation during pregnancy differs and requires specific clinical advice.
Tips for accurate results
For a useful home reading, sit quietly for five minutes with your back supported, feet flat, and your arm resting at heart level. Use a correctly sized cuff, avoid caffeine and exercise for 30 minutes beforehand, and take two readings a minute apart. Comparing several readings over days is more informative than a single number.
Common mistakes and limits
In adults, the American Heart Association categories are: normal below 120/80, elevated 120 to 129 with a diastolic under 80, stage 1 hypertension 130 to 139 or 80 to 89, and stage 2 at 140/90 or higher. A reading above 180/120, especially with chest pain, shortness of breath, or vision or speech changes, needs urgent medical care. This tool cannot diagnose anything, so discuss repeated high readings with a clinician.