Blood pressure reading includes systolic and diastolic pressure values. Systolic blood pressure is the pressure peak when the heart beats while pumping blood. Diastolic blood pressure is the pressure drop when the heart is at rest between beats.
Often blood pressure levels are written with the systolic number above or before the diastolic, such as 120/80 mmHg. (The mmHg is millimeters of mercury the unit to measure pressure.)
Blood pressure level chart in mmHg
| Category | Systolic | Diastolic | |
| Normal | less than 120 | and | less than 80 |
| Pre Hypertension | 120 to 139 | or | 80 to 89 |
| Hypertension (stage 1) | 140 to 159 | or | 90 to 99 |
| Hypertension (stage 2) | greater or equal to 160 | or | greater or equal to 100 |
When systolic and diastolic blood pressures fall into different categories, should use the higher category to classify blood pressure levels. For example, 150/79 mmHg would be stage 1 hypertension.