Mean Arterial Pressure (MAP) Calculator

Mean arterial pressure (MAP) is the average pressure in your arteries over one complete heartbeat, accounting for the fact that the heart spends more time relaxed (diastole) than contracted (systole). It's a single number clinicians use to assess how well organs are being perfused with blood.

What MAP Measures

MAP isn't a simple average of systolic and diastolic pressure, it's weighted to reflect that diastole lasts roughly twice as long as systole during a normal heartbeat, so diastolic pressure counts for more in the calculation.

The Formula

MAP = Diastolic + (1/3 x (Systolic - Diastolic))

This is equivalent to MAP = (Systolic + 2 x Diastolic) / 3. The one-third weighting is a standard approximation used at typical resting heart rates².

How This Calculator Computes Your Result

Enter your systolic and diastolic blood pressure readings. We apply the formula above and show your MAP alongside the typical normal range.

What Your Result Means

A normal MAP generally falls between about 70 and 100 mmHg. In critical care medicine, a MAP of roughly 65 mmHg is commonly used as the minimum resuscitation target for critically ill patients, below which organ perfusion is considered to be at risk¹.

Where the 65 mmHg Threshold Comes From

The 65 mmHg figure comes from critical care guidelines for treating sepsis and septic shock, where maintaining adequate blood flow to organs like the kidneys and brain is a life-or-death concern, not from research on healthy ambulatory adults. Current international sepsis treatment guidelines recommend an initial MAP target of 65 mmHg for patients in septic shock as part of resuscitation efforts¹. A healthy person with a MAP reading near that number is not in the situation this threshold was designed for, it's a treatment target for critically ill patients, not a general-population warning sign.

Why 1/3, Not a Simple Average

A heartbeat isn't split evenly between contraction and relaxation, at a typical resting heart rate, the heart spends roughly twice as long relaxed (diastole) as it does contracting (systole). Since arterial pressure sits closer to diastolic pressure for most of that cycle, weighting diastolic pressure twice as heavily gives a more accurate average than simply splitting the difference between the two readings². At faster heart rates, the ratio of systole to diastole shifts, which is the main reason this one-third weighting is an approximation rather than an exact formula for every individual.