Blood pressure is recorded as two numbers — for example, 120/80, read as “120 over 80”:
- The top (systolic) number measures pressure when the heart contracts and pushes blood out.
- The bottom (diastolic) number measures pressure between beats, while the heart rests.
Current categories: normal is below 120/80; elevated is 120–129 systolic with diastolic below 80; stage 1 hypertension is 130–139 or 80–89; stage 2 is 140/90 or higher. A reading above 180/120 needs prompt medical attention.
One high reading does not equal hypertension — stress, caffeine, pain, or even rushing to the appointment can spike it temporarily (the classic “white coat” effect). Diagnosis rests on repeated, properly taken measurements, sometimes including home monitoring. Because high blood pressure usually causes no symptoms while quietly damaging arteries, knowing your numbers is one of the simplest high-value habits in medicine.
Further reading: what high blood pressure is (American Medical Association)