Mean Arterial Pressure Calculator
Calculate mean arterial pressure (MAP) from a blood pressure reading. Enter systolic and diastolic in mmHg to get MAP, pulse pressure, and where the result falls relative to the ≥ 65 mmHg perfusion target.
Example: with Systolic (top number) 120 · Diastolic (bottom number) 80 → Mean arterial pressure: 93.3 mmHg.
- Pulse pressure40 mmHg (systolic − diastolic)
- InterpretationNormal perfusion range
- FormulaMAP = 80 + (120 − 80)/3 = 80 + 40/3
Computed by the calculator below using its default values. Change any input to see your own numbers.
MAP = DBP + (SBP − DBP)/3, because at a normal heart rate the heart spends about two-thirds of each beat in diastole. Critical-care teams aim for MAP ≥ 65 mmHg.
What MAP tells you that a BP reading doesn't
Mean arterial pressure is the average pressure pushing blood through your organs across a full heartbeat, and it is what perfusion actually depends on. Because the heart rests in diastole about twice as long as it contracts in systole, MAP sits closer to the diastolic number than a simple midpoint: MAP = diastolic + one-third of the pulse pressure. For a textbook 120/80, that is 80 + 40/3 ≈ 93 mmHg.
Clinicians watch MAP because organs like the brain and kidneys need roughly 60–70 mmHg to stay perfused; intensive-care targets are commonly set at 65 mmHg or above. Pulse pressure, the gap between systolic and diastolic, is a second clue — a very wide or very narrow gap can matter as much as the average.
How it’s calculated
MAP = DBP + (SBP − DBP)/3 = DBP + PP/3, equivalent to (SBP + 2×DBP)/3. Pulse pressure = SBP − DBP. Perfusion target ≥ 65 mmHg from critical-care guidance (e.g., Surviving Sepsis Campaign). The tool requires systolic ≥ diastolic.
The one-third rule assumes a resting heart rate near 60–100; at high rates diastole shortens and true MAP runs higher than the estimate. A single reading is not a diagnosis. Not medical advice.
MAP interpretation bands
| MAP (mmHg) | Interpretation | Note |
|---|---|---|
| < 60 | Too low | Organs may not perfuse; emergency |
| 60-69 | Borderline low | ≥ 65 is a common ICU target |
| 70-100 | Normal | Healthy perfusion range |
| 101-110 | Elevated | Monitor; possible hypertension |
| > 110 | High | Sustained load on vessels and organs |
MAP = DBP + (SBP − DBP)/3; perfusion target ≥ 65 mmHg per critical-care guidance.
Common mistakes
- Averaging systolic and diastolic evenly — MAP weights diastole two-to-one, not fifty-fifty.
- Applying the one-third rule at a very high heart rate, where it underestimates MAP.
- Reading one number as a diagnosis; trends and symptoms matter more than a single value.
- Entering diastolic above systolic, which is not a valid reading.
Frequently asked questions
What is the formula for mean arterial pressure?
MAP = diastolic + (systolic − diastolic)/3, the same as (systolic + 2 × diastolic)/3. For 120/80 it is about 93 mmHg.
What is a normal MAP?
Roughly 70 to 100 mmHg. Critical-care teams often aim to keep MAP at or above 65 mmHg to keep organs perfused.
Why isn't MAP just the average of the two numbers?
Because the heart spends about twice as long in diastole as in systole at rest, so the diastolic pressure gets double weight in the average.
Should I act on a MAP I calculate at home?
Use it for context, not diagnosis. A single reading can mislead; discuss concerning or symptomatic values with a clinician rather than self-treating.