Mean Arterial Pressure (MAP): Formula, Normal Range & Meaning
Mean arterial pressure is the average pressure driving blood to your organs across the whole cardiac cycle — and it, more than the systolic number, is what perfusion depends on.
What is mean arterial pressure?
Mean arterial pressure (MAP) is the average blood pressure in the arteries over one cardiac cycle. Because the heart spends about two-thirds of each cycle in diastole, MAP sits closer to the diastolic than the systolic pressure — and it's the number that best reflects organ perfusion.
Mean arterial pressure formula
MAP = diastolic BP + ⅓ × (systolic BP − diastolic BP)
Equivalently, MAP = (systolic + 2 × diastolic) ÷ 3. For a blood pressure of 120/80, MAP is about 93 mmHg. Try it in the MAP calculator. In practice, MAP can also be measured directly by an arterial line, and is derived from cardiac output and systemic vascular resistance.
Normal MAP range
| MAP | Interpretation |
|---|---|
| 70–100 mmHg | Normal |
| ≥ 65 mmHg | Generally adequate organ perfusion |
| < 60 mmHg | Risk of organ hypoperfusion |
A MAP of at least 65 mmHg is a common resuscitation target in shock, because below it the kidneys, brain, and other organs begin to lose their ability to autoregulate blood flow.
Why MAP matters more than systolic pressure
Organs are perfused throughout the cardiac cycle, not just at the systolic peak, so the average pressure is what counts. That's why critical-care and cath-lab teams titrate vasopressors to a MAP goal rather than to systolic pressure. MAP is also the driving pressure in the formula for systemic vascular resistance, tying it directly to afterload and cardiac output.
High and low MAP
- Low MAP — shock states, sepsis, blood loss, over-aggressive antihypertensives; risks organ hypoperfusion.
- High MAP — chronic hypertension, high vascular resistance, raised intracranial pressure responses; increases cardiac workload.
Key takeaways
- MAP is the average arterial pressure over the cardiac cycle.
- MAP = DBP + ⅓ × (SBP − DBP); normal is 70–100 mmHg.
- A MAP of at least 65 mmHg is the usual perfusion target in shock.
- It reflects organ perfusion better than systolic pressure alone.
Calculate MAP
Enter systolic and diastolic pressure to get the mean arterial pressure.
Open the MAP Calculator →Frequently asked questions
What is a normal mean arterial pressure?
About 70–100 mmHg. A MAP of at least 65 mmHg is generally needed for adequate organ perfusion.
What is the MAP formula?
MAP = diastolic BP + ⅓ × (systolic − diastolic), which is the same as (systolic + 2 × diastolic) ÷ 3.
Why is a MAP of 65 important?
Below roughly 65 mmHg the organs lose their ability to autoregulate blood flow, so 65 mmHg is a common resuscitation target in shock.
Why is MAP more useful than systolic blood pressure?
Organs are perfused across the whole cardiac cycle, so the average pressure (MAP) reflects perfusion better than the systolic peak.
What causes a low MAP?
Shock, sepsis, blood loss, and over-treatment with antihypertensive or vasodilator drugs.
How is MAP related to cardiac output?
MAP is approximately cardiac output multiplied by systemic vascular resistance (plus central venous pressure), so it links flow and resistance.
Sources & further reading
- Cardiovascular Credentialing International (CCI)
- American College of Cardiology
- American Heart Association
- MedlinePlus (U.S. National Library of Medicine)
External links are provided for reference; always confirm current details with the official source.