Mean Arterial Pressure Calculator
Compute Mean Arterial Pressure (MAP) from a standard blood pressure reading in seconds. Clinicians use MAP to assess whether vital organs are receiving adequate perfusion.
About this calculator
Mean Arterial Pressure (MAP) is the average pressure in the arteries during one complete cardiac cycle and is considered a better indicator of organ perfusion than systolic pressure alone. The standard clinical formula is MAP = diastolic + (systolic − diastolic) / 3. This is mathematically equivalent to (systolic + 2 × diastolic) / 3, reflecting the fact that the heart spends roughly twice as long in diastole as in systole. Pressures are measured in millimetres of mercury (mmHg). A normal MAP is generally 70–100 mmHg. Values below 60 mmHg are associated with inadequate perfusion to vital organs such as the brain and kidneys. MAP is routinely monitored in intensive care, anaesthesia, and during sepsis management.
How to use
Example: a patient has a systolic pressure of 120 mmHg and a diastolic pressure of 80 mmHg. Step 1 — Find pulse pressure: 120 − 80 = 40 mmHg. Step 2 — Divide by 3: 40 ÷ 3 ≈ 13.3 mmHg. Step 3 — Add diastolic: 80 + 13.3 = 93.3 mmHg. The MAP is approximately 93 mmHg, which sits comfortably within the normal range of 70–100 mmHg. Enter your own systolic and diastolic values above to calculate MAP instantly.
Frequently asked questions
What is a dangerous MAP level and when should I seek medical attention?
A MAP below 60 mmHg is considered critically low and indicates that vital organs — including the brain, kidneys, and heart — may not be receiving enough blood flow, a condition that can lead to organ failure if untreated. This is a medical emergency often seen in septic or haemorrhagic shock. On the upper end, a sustained MAP above 110 mmHg signals severe hypertension and significantly raises the risk of stroke, myocardial infarction, and renal damage. If you measure values outside the 70–100 mmHg normal range, consult a healthcare professional promptly.
Why is MAP considered more important than systolic blood pressure in clinical settings?
Systolic pressure fluctuates significantly with cardiac cycle, stress, and movement, while MAP smooths these variations to represent the true driving pressure for tissue perfusion throughout the entire cycle. Critical care guidelines for conditions like sepsis specify MAP targets (typically ≥65 mmHg) rather than systolic targets because MAP more directly correlates with organ blood flow. Additionally, MAP is what the body's baroreceptors and autoregulation mechanisms actively defend, making it the physiologically relevant pressure. Anaesthesiologists, intensivists, and emergency physicians therefore prioritise MAP when titrating vasopressors and IV fluids.
How does the formula MAP = diastolic + (systolic − diastolic) / 3 account for heart rhythm?
The formula is derived from the observation that in a normal resting heart rate of 60–80 bpm, systole (contraction) occupies approximately one-third of the cardiac cycle and diastole (relaxation) occupies the other two-thirds. Pressure is higher during systole and lower during diastole, so the time-weighted average weights diastolic pressure twice as heavily. This gives MAP = (systolic + 2 × diastolic) / 3, which is algebraically identical to diastolic + (systolic − diastolic) / 3. At very high heart rates, diastole shortens and the true MAP shifts slightly higher, which is why direct arterial line measurement is preferred in critically ill patients.