Mean arterial pressure (MAP) is the average pressure in the arteries during one cardiac cycle, weighted towards diastole because the heart spends more of each cycle in diastole than systole. It is used in intensive care and anaesthesia as a more reliable indicator of organ perfusion than systolic pressure alone.
This calculator uses the standard approximation MAP = DBP + ⅓(SBP − DBP), where SBP is systolic blood pressure and DBP is diastolic blood pressure. Because diastole lasts roughly twice as long as systole in a normal cardiac cycle, diastolic pressure is weighted more heavily than systolic pressure in the average. The same formula is sometimes written as (SBP + 2 × DBP) ÷ 3 — both give an identical result.
MAP is the pressure that actually drives blood flow into organs such as the brain, kidneys, and coronary arteries. A MAP of at least 60 mmHg is widely cited as the minimum generally needed to maintain adequate perfusion of vital organs; sustained pressure below this can lead to ischaemia. This is why MAP, rather than systolic or diastolic pressure alone, is the figure most commonly targeted and monitored in critical care and anaesthesia.
The 60 mmHg figure is a population-based guide, not a fixed target for every patient — individual perfusion requirements vary with baseline blood pressure, chronic conditions, and the specific organ or clinical situation being managed. This calculator gives a numerical estimate only; it does not offer a diagnosis or management recommendation and is not a substitute for clinical judgement. Always interpret the result in the context of the full clinical picture.
Formula and perfusion threshold: Physiology, Mean Arterial Pressure — StatPearls, NCBI Bookshelf.