Blood Pressure Average Calculator Blood Pressure Average Calculator # Systolic (mm Hg) Diastolic (mm Hg) Action Add Reading Calculate Average Clear All No averages calculated yet. How To Use Blood Pressure Average CalculatorEnter your systolic and diastolic readings in each row.You can click “Add reading” to enter more values.When finished, click “Calculate average.”The tool will display your average blood pressure and AHA category.To start over, click “Clear all.”