Mean Arterial Pressure Calculator

MAP from systolic and diastolic, with perfusion thresholds.

Calculate mean arterial pressure from systolic and diastolic blood pressure, with the 65 mmHg perfusion threshold and pulse pressure.

Written and maintained by Mohit PatelLast checked August 4, 2026How we build these

Systolic

mmHg

Diastolic

mmHg

Mean arterial pressure

93 mmHg

within the usual range

Pulse pressure40 mmHg

Systolic120 mmHg

Diastolic80 mmHg

Normal MAP range70–100 mmHg

How the Mean Arterial Pressure Calculator works

Mean arterial pressure is the average pressure driving blood into the tissues across a full cardiac cycle. Because the heart spends roughly twice as long in diastole as in systole, MAP sits closer to the diastolic figure than a simple average would suggest.

Also known as: MAP calculator · mean arterial pressure formula · average blood pressure calculator

What mean arterial pressure represents

Mean arterial pressure is the average pressure in the arteries across a cardiac cycle, and it is the pressure that actually drives blood into the organs. Systolic and diastolic are the peaks and troughs; MAP is what the tissues experience on average.

The standard estimate is diastolic pressure plus one third of the pulse pressure, where pulse pressure is systolic minus diastolic. For 120 over 80, that is 80 plus one third of 40, giving 93.

The one third weighting reflects that the heart spends roughly twice as long in diastole as in systole at normal heart rates. At high heart rates that ratio changes and the formula becomes less accurate, which is one reason invasive monitoring measures MAP directly rather than calculating it.

Why perfusion depends on it

Organ blood flow depends on the pressure gradient across the organ's vascular bed, and MAP is the driving pressure at the input.

A MAP of around 60 to 65 millimetres of mercury is conventionally treated as the lower boundary for adequate perfusion of the brain and kidneys in adults, and it is a rule of thumb rather than a physiological constant.

Autoregulation maintains flow across a range of pressures, and the range shifts in people with chronic hypertension, whose organs have adapted to higher pressures. That is why a MAP that would be adequate in one patient may not be in another, and why targets are individualised in critical care.

Where it is used in practice

Critical care uses MAP targets for vasopressor titration in shock, because it correlates with perfusion better than systolic pressure does.

Cerebral perfusion pressure is calculated as MAP minus intracranial pressure, which makes MAP central to the management of traumatic brain injury.

It appears in sepsis guidelines, in anaesthesia, and in the management of any condition where maintaining organ perfusion is the immediate objective. In each case the target comes from a protocol rather than from a general figure.

The limits of the estimate

The formula assumes a normal heart rate and a normal arterial waveform. In tachycardia the proportion of the cycle spent in diastole falls, and the one third weighting overestimates the diastolic contribution.

In aortic regurgitation, in severe arrhythmia and with an intra-aortic balloon pump, the calculated value diverges further from the measured one.

Non-invasive cuff measurements also carry their own error, particularly in shock where peripheral vasoconstriction makes cuff readings unreliable. In those situations an arterial line measures MAP directly, and the calculation is not used.

What this page is and is not

This calculator performs a subtraction, a division and an addition. It has no access to a patient, a monitor, a history or a protocol.

Interpreting a MAP requires all of those. A value of 62 is reassuring in one patient and an emergency in another, and nothing on this page can distinguish them.

Anyone using this professionally will have their own protocols and their own checks, and this is a convenience for verifying arithmetic. Anyone using it about their own blood pressure should take the reading to a doctor rather than to a calculation, because the systolic and diastolic figures are what clinical guidance is written around.

Where to go next

The Mean Arterial Pressure question rarely arrives on its own. These are the ones that usually come with it:

Blood Pressure Category Calculator — Where a reading falls on the ACC/AHA scale.
Cholesterol Ratio Calculator — Total:HDL, LDL:HDL and triglyceride ratios.
Max Heart Rate Calculator — Four formulas, because 220 minus age is the worst of them.
BMI Calculator — Body mass index with category and healthy weight range.

Sources

NHS, Health A to Z

Not medical advice. This calculator gives a general estimate, not medical advice. It cannot account for your individual health, medical history, or medication. Talk to a qualified healthcare professional before acting on any result.

Frequently asked questions

How is mean arterial pressure calculated?

MAP = diastolic + (systolic − diastolic) ÷ 3, which is equivalent to (2 × diastolic + systolic) ÷ 3. The weighting reflects the proportion of the cardiac cycle spent in diastole at a normal heart rate.

What is a normal mean arterial pressure?

Roughly 70-100 mmHg. A MAP of at least 60-65 mmHg is generally considered the minimum needed to perfuse the vital organs, which is why 65 is a common resuscitation target in sepsis guidance.

Why use MAP rather than systolic pressure?

Because organ perfusion depends on the average driving pressure, not the peak. In critical care, MAP is the value titrated against, since a high systolic with a very low diastolic can leave tissues underperfused despite a reassuring top number.

Does the formula hold at high heart rates?

Less well. The one-third weighting assumes a normal ratio of systole to diastole; at tachycardic rates diastole shortens disproportionately and the estimate drifts. Invasive arterial monitoring measures MAP directly rather than inferring it.