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MAP

General

Mean Arterial Pressure

The average blood pressure in a person's arteries during one complete cardiac cycle — a key indicator of the perfusion pressure reaching vital organs.

Definition

MAP (Mean Arterial Pressure) is the average pressure in a person's arteries during a single complete cardiac cycle — encompassing both the contraction phase (systole) and the relaxation/filling phase (diastole). It represents the actual driving pressure that pushes blood through the circulatory system to reach organs and tissues.

MAP is used to:

  • Assess whether blood flow to vital organs (brain, kidneys, heart) is adequate
  • Guide fluid and medication management in intensive care and during surgery
  • Monitor patients in shock, trauma, or major blood loss situations
  • Complement systolic/diastolic readings with a single perfusion-focused number

Because organs need a minimum sustained pressure to stay adequately perfused, MAP is often more clinically actionable in critical settings than systolic or diastolic pressure alone.

Formula

MAP = DBP + ⅓ (SBP − DBP)

Where SBP = Systolic Blood Pressure and DBP = Diastolic Blood Pressure.

This can also be written as:

MAP = (SBP + 2 × DBP) ÷ 3

Both forms give the same result — they reflect that diastole lasts roughly twice as long as systole in a normal cardiac cycle.

Worked Example

A patient has a blood pressure reading of 120/80 mmHg (SBP = 120, DBP = 80).

MAP = 80 + ⅓ (120 − 80) = 80 + ⅓ (40) = 80 + 13.3 = 93.3 mmHg

Interpretation: This patient's Mean Arterial Pressure of about 93 mmHg falls within the normal range (70-100 mmHg), indicating adequate perfusion pressure. Use the MAP calculator to compute MAP from any blood pressure reading.

Key Things to Know

  • MAP is not a simple average of SBP and DBP: Because diastole lasts about twice as long as systole in each cardiac cycle, the formula weights diastolic pressure more heavily rather than averaging the two values equally.
  • 65 mmHg is a common critical care target: In sepsis and shock management, clinicians commonly target a MAP of at least 65 mmHg with fluids or vasopressor medications to maintain organ perfusion.
  • MAP changes with heart rate: Faster heart rates shorten the relative time spent in diastole, which can shift the true physiological MAP slightly from the simplified formula — the formula is a well-validated approximation, not an exact measurement.
  • MAP and ABI measure different things: MAP reflects overall central arterial pressure, while ABI compares localized pressure readings between the ankle and arm to detect blocked leg arteries — both use blood pressure cuffs but answer different clinical questions.
  • Exercise and MAP: During exercise, MAP typically rises due to increased systolic pressure and cardiac output, which is one reason target heart rate zones and blood pressure response are both monitored together in cardiac stress testing.

Related Calculators

MAP Calculator (Mean Arterial Pressure) →Calculate mean arterial pressure (MAP) from systolic and diastolic blood pressure to check organ perfusion adequacy, with normal range context.

Related Terms

ABIAnkle-Brachial IndexTarget Heart RateExercise Intensity Heart Rate Zone

Frequently Asked Questions

A normal Mean Arterial Pressure for a healthy adult falls between 70 and 100 mmHg. Values below 60 mmHg are generally considered too low to reliably perfuse vital organs like the brain, heart, and kidneys, while sustained values above 100-110 mmHg may indicate hypertension requiring evaluation. Use the [MAP calculator](/map-calculator/) to compute your MAP from a standard blood pressure reading.
Systolic and diastolic pressure represent the peak and trough of each heartbeat, but organs are perfused throughout the entire cardiac cycle, not just at those two points. MAP accounts for the fact that the heart spends more time in diastole than systole, giving a more accurate picture of the actual average pressure driving blood flow to tissues — which is why it's the preferred metric in critical care and anesthesia settings.
The heart spends roughly two-thirds of each cardiac cycle in diastole (relaxation/filling) and one-third in systole (contraction), so the diastolic pressure contributes more to the time-averaged pressure. This is reflected in the formula, which adds only one-third of the pulse pressure (the systolic-diastolic difference) to the diastolic value, rather than a simple 50/50 average.
A MAP below approximately 60 mmHg is often used as a threshold below which organ perfusion — particularly to the kidneys and brain — becomes inadequate, a state seen in shock or severe blood loss. This is why MAP is continuously monitored in intensive care units and during major surgery, often with a target to keep MAP above 65 mmHg using fluids or medications.
Both MAP and the [Ankle-Brachial Index (ABI)](/glossary/abi/) are derived from blood pressure measurements but serve different purposes: MAP summarizes overall arterial pressure driving organ perfusion, while ABI compares pressure readings at two different body sites (ankle vs. arm) to screen for blocked arteries in the legs. A patient's MAP can be normal while their ABI still indicates peripheral artery disease.