π©Ί Mean Arterial Pressure (MAP) Calculator
The perfusion pressure behind the BP numbers.
For informational purposes only, not medical advice. Consult a healthcare professional.
Mean arterial pressure is the average pressure driving blood through your organs across the whole cardiac cycle. It matters more than systolic or diastolic alone because organs care about steady perfusion, not peaks. The formula weights diastole twice because the heart spends about two-thirds of each cycle at rest: MAP equals diastolic plus one-third of the pulse pressure.
Enter systolic and diastolic in mmHg. The calculator returns MAP and flags the key threshold: 65 mmHg, the minimum most ICU protocols target to keep kidneys, brain, and gut perfused.
How to Use This Calculator
Enter the systolic (top) and diastolic (bottom) numbers from the blood pressure reading. Read the MAP. In critical care, 65 mmHg is the standard floor; at home, use MAP as context for what a low or high reading means for perfusion, not as a target to chase alone.
Enter systolic and diastolic pressure in mmHg.
Read the MAP.
Check it against 65 mmHg if perfusion is the question.
Discuss persistent abnormal values with your clinician.
Why Diastole Counts Double
Each heartbeat is roughly one-third systole (ejection) and two-thirds diastole (filling and rest). The true mean pressure is the time-weighted average, which works out to diastole plus a third of the pulse pressure. Arterial lines measure MAP directly as the waveform's mean and it is the most accurate number on the monitor; cuffs estimate it from oscillations and derive systolic and diastolic from it, which is the reverse of what most people assume. At very high heart rates the systole/diastole split shifts and the one-third rule gets less exact.
Worked Example
A BP of 120/80 gives a MAP of 93 mmHg, in the Normal perfusion range. A BP of 90/60 gives MAP 70: the systolic looks alarming but perfusion pressure is still adequate, which is why ICU teams titrate vasopressors to MAP rather than systolic. Below 60, organs start going hungry.
Reading Your MAP
Normal resting MAP runs about 70 to 100 mmHg. Below 65, organ perfusion suffers: the kidneys cut urine output first, then mentation dulls. That 65 threshold comes from sepsis and shock protocols where titrating vasopressors to MAP 65 improved outcomes versus lower targets. Above 100-110 at rest usually reflects hypertension needing the usual workup. A wide pulse pressure (high systolic, low diastolic) with normal MAP suggests stiff arteries, common with aging.
One Reading Is Not a Diagnosis
Blood pressure varies through the day and with cuff size, arm position, caffeine, and stress. A single low MAP with symptoms (dizziness, faintness, confusion) deserves prompt care; a single high reading deserves a recheck, not panic. People on blood pressure medications should follow their doctor's plan rather than adjusting doses to a calculator. For informational purposes only, not medical advice. Consult a healthcare professional.
Related tools: blood pressure checker, mean airway pressure (ventilator) and MELD score.
For informational purposes only, not medical advice. Consult a healthcare professional.
Frequently Asked Questions
What is a normal MAP?
About 70 to 100 mmHg at rest. ICU protocols target at least 65 mmHg to maintain organ perfusion in shock.
How do you calculate MAP?
Diastolic plus one-third of the pulse pressure: MAP = DBP + (SBP - DBP)/3. For 120/80 that is 93.
Why is 65 the MAP target in sepsis?
Trials and guidelines found 65 mmHg the practical floor where organ perfusion is maintained; higher targets did not improve outcomes and needed more vasopressors.
Is MAP more important than systolic?
For organ perfusion, yes: it is the steady driving pressure. Systolic matters more for stroke risk and cardiac workload over years.
What causes low MAP?
Dehydration, blood loss, sepsis, heart failure, and blood pressure medications. Symptoms include dizziness, fainting, and confusion.
Can MAP be too high?
Chronically, yes: it reflects hypertension and its organ risks. Acutely very high MAP can signal hypertensive emergency with symptoms.
Why does diastole count twice?
The cardiac cycle is about one-third systole and two-thirds diastole, so the time-weighted average weights diastolic pressure double.
Do home cuffs measure MAP?
They estimate it from cuff oscillations, then derive systolic and diastolic. Arterial lines measure MAP directly and more accurately.
Why do ICU teams target MAP 65 instead of a systolic number?
Organs care about the average driving pressure across the whole cardiac cycle, not the peak. A MAP of 65 mmHg is the lowest level that reliably keeps blood flowing to the brain and kidneys in most adults; below 60, autoregulation fails and organ injury starts. Systolic pressure can look fine while MAP is dangerously low, which is why the ICU watches MAP.
Can MAP be too high?
Yes. Sustained MAP above 100 to 110 raises the workload on the heart and can worsen bleeding, strain fresh surgical repairs, and push stroke risk up in vulnerable patients. Blood pressure management is a band, not a floor: enough to perfuse organs, low enough to avoid damage.