Mean arterial pressure calculator
Mean arterial pressure from a systolic and diastolic reading.
Optional. Used only to flag where the approximation weakens.
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This is a reference implementation of a published formula, provided for use by qualified healthcare professionals. It does not diagnose, does not account for the individual circumstances of any patient, and is not a recommendation for treatment. Confirm every result against your own institutional guidance before acting on it. Clinical judgement always takes precedence over a calculator.
About this calculation
Mean arterial pressure approximates the average pressure driving perfusion across the cardiac cycle. Because diastole occupies roughly twice as much of the cycle as systole, it is weighted two to one rather than being a simple average.
Formula
MAP ≈ DBP + ⅓ × (SBP − DBP)
- Source
- Standard haemodynamic approximation
- Methodology version
- 1.0.0
- Last reviewed
- 2026-10-28
What this does not account for
- The one-third weighting assumes a normal heart rate. At a tachycardia, diastole shortens disproportionately and the formula overestimates MAP.
- It is an approximation of the true area under the arterial pressure curve. An arterial line measures MAP directly and should be preferred when one is in place.
- The formula says nothing about whether perfusion is adequate for a given patient, which depends on their usual pressure.