Mean Arterial Pressure (MAP) Calculator
Work out mean arterial pressure from a systolic and diastolic blood-pressure reading, with pulse pressure and a perfusion-range check.
How it works
MAP = (SBP + 2 × DBP) ÷ 3 = DBP + ⅓ × (SBP − DBP) · Pulse pressure = SBP − DBP
Mean arterial pressure is the average pressure pushing blood through the arteries across one cardiac cycle, and it is the number that best reflects organ perfusion. Because the heart spends about twice as long in diastole as in systole, diastolic pressure is weighted double in the estimate. A MAP of at least 60 mmHg is generally considered the minimum to perfuse the brain, heart and kidneys, and 70–100 mmHg is a common target — though this two-thirds/one-third estimate is less exact at very high heart rates.
Worked example
For a blood pressure of 120/80 mmHg: MAP = (120 + 2 × 80) ÷ 3 = 280 ÷ 3 = 93.3 mmHg, and the pulse pressure is 120 − 80 = 40 mmHg — both comfortably in the normal range.
Sources: Mean arterial pressure
Frequently asked questions
Why is diastolic pressure counted twice?
At a normal heart rate the heart spends roughly two-thirds of each cycle in diastole and one-third in systole, so diastolic pressure contributes more to the time-averaged pressure. The 1:2 weighting approximates that.
What MAP is too low?
A MAP below about 60 mmHg is often used as a threshold where organ perfusion becomes inadequate; many critical-care protocols aim to keep it at 65 mmHg or higher. The right target depends on the individual and their condition.
How does MAP differ from pulse pressure?
MAP is the average perfusion pressure across the cycle, while pulse pressure is the difference between systolic and diastolic — a marker of arterial stiffness and stroke volume. They describe different things.
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Educational estimate using standard published formulas — not medical advice, a diagnosis, or a substitute for clinical judgement. Dosing, diagnosis and treatment must be decided by a qualified clinician using validated tools and the full clinical picture.