Calculate mean arterial pressure and pulse pressure from systolic and diastolic readings, with the blood pressure category.
mmHg
mmHg
Enter the values to see the result here.
Calculation aids only. They do not replace clinical judgement or the drug reference. Verify every dose before using it on a patient.
Formula
With systolic pressure SBP and diastolic pressure DBP:
MAP=DBP+3SBP−DBPPP=SBP−DBP
The category uses the 2017 ACC/AHA bands: normal below 120/80, elevated 120 to 129 with diastolic under 80, stage 1 at 130/80 and stage 2 at 140/90 or higher.
Worked example
A patient measures 130/85 mmHg.
Pulse pressure: 130−85=45 mmHg.
MAP=85+45/3=100 mmHg.
Category: stage 1 hypertension, since both numbers are at or above the stage 1 cut-offs.
A reading of 90/60 gives a MAP of 70 mmHg, which is above the usual minimum of 65.
Common mistakes
Swapping the two numbers. The first is systolic, the second diastolic.
Treating one reading as a diagnosis. Hypertension is confirmed on at least two occasions with correct technique.
Using the formula at a very fast heart rate, where the one-third rule is less accurate.
Ignoring symptoms. A normal-looking number does not rule out a problem in a patient who feels unwell.
Frequently asked questions
Why is MAP not just the average of the two numbers?
The heart spends about two thirds of each beat in diastole and one third in systole, so the mean pressure sits closer to the diastolic value. The one-third rule weights the pulse pressure accordingly.
What MAP is considered too low?
Below about 65 mmHg many organs, especially the kidneys and brain, can be under-perfused, which is why 65 is a common treatment target in shock. Individual targets differ, for example in chronic hypertension.
What does a wide pulse pressure mean?
A pulse pressure above about 60 mmHg often reflects stiff arteries in older adults, and can also occur with aortic regurgitation, fever or anaemia. A very narrow one can signal low stroke volume. It is a clue for the clinician, not a diagnosis.