Calculate MAP from systolic and diastolic blood pressure. Includes pulse pressure, shock index, rate-pressure product, and BP classification.
Mean arterial pressure (MAP) represents the average blood pressure in the arteries during one complete cardiac cycle. Unlike a simple average of systolic and diastolic pressures, MAP accounts for the fact that the heart spends approximately twice as long in diastole as in systole at normal heart rates. The standard formula — MAP = DBP + ⅓(SBP − DBP) — weight diastolic pressure more heavily, reflecting this physiological reality.
MAP is the primary determinant of organ perfusion and is arguably more clinically significant than systolic or diastolic pressure alone. A MAP of at least 65 mmHg is generally considered the minimum needed to adequately perfuse the brain, kidneys, and coronary arteries. In critical care settings, MAP is the hemodynamic target for vasopressor titration in septic shock, the threshold for cerebral perfusion pressure calculations in traumatic brain injury, and a key parameter in post-cardiac surgery management.
This calculator computes MAP along with several important derived parameters: pulse pressure (the difference between systolic and diastolic, reflecting arterial compliance and stroke volume), the shock index (HR/SBP, a quick marker of hemodynamic instability), the rate-pressure product (an index of myocardial oxygen demand), and systemic vascular resistance when cardiac output data is available. The ACC/AHA 2017 blood pressure classification is also provided for hypertension staging.
MAP is the cornerstone hemodynamic parameter used in critical care, emergency medicine, and cardiology. This calculator provides MAP alongside essential derived parameters for a complete hemodynamic snapshot. Keep these notes focused on your operational context. Tie the context to the calculator’s intended domain. Use this clarification to avoid ambiguous interpretation. Align this note with review checkpoints.
MAP = DBP + ⅓(SBP − DBP), equivalently MAP = (2 × DBP + SBP) / 3. Pulse Pressure = SBP − DBP. Shock Index = HR / SBP. Rate-Pressure Product = SBP × HR. SVR = [(MAP − CVP) / CO] × 80.
Result: 93.3 mmHg
With SBP 120 and DBP 80 mmHg: MAP = 80 + (120 − 80)/3 = 93.3 mmHg. This falls within the normal range (70–105 mmHg) and exceeds the 65 mmHg minimum for organ perfusion.
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A normal MAP is typically 70–105 mmHg. MAP ≥ 65 mmHg is the minimum generally needed for adequate organ perfusion. MAP > 105 mmHg may indicate hypertension.
MAP represents the true driving pressure for organ perfusion averaged over the cardiac cycle. It accounts for the proportion of time spent in systole vs. diastole, making it more physiologically meaningful.
Pulse pressure (SBP − DBP) reflects arterial compliance and stroke volume. Normal PP is 30–40 mmHg. Widened PP (> 60) can indicate aortic regurgitation, arterial stiffness, or hyperthyroidism.
The shock index (HR/SBP) normally ranges from 0.5 to 0.7. Values > 0.9 suggest hemodynamic compromise, and > 1.3 indicates severe shock with need for immediate intervention.
MAP is the primary vasopressor target in septic shock (target ≥ 65 mmHg), is used to calculate cerebral perfusion pressure (CPP = MAP − ICP), and guides postoperative hemodynamic management. Use this as a practical reminder before finalizing the result.
The standard formula assumes normal heart rates. At very fast rates (diastolic time shortens), MAP may be slightly higher than the formula predicts. At bradycardic rates, MAP may be slightly lower.