A person's normal blood pressure should have a systolic pressure (the higher value) ranging from 100 to 120 mmHg and a diastolic pressure (the lower value) ranging from 60 to 80 mmHg.

If you want to diagnose whether a person has hypertension, generally speaking, the systolic pressure needs to be greater than or equal to 140 mmHg or the diastolic pressure needs to be greater than or equal to 90 mmHg.

Moreover, a single blood - pressure measurement cannot be used to diagnose hypertension. Three measurements on non - consecutive days are required. If the blood pressure is high in all three measurements, then hypertension can be diagnosed.