The mean arterial pressure calculator computes MAP from systolic and diastolic blood pressure readings using the standard formula: MAP = (Systolic + 2 × Diastolic) ÷ 3. MAP is the average pressure in the arterial circulation throughout the cardiac cycle and is the key haemodynamic parameter used to assess adequate organ perfusion. A MAP of at least 60–65 mmHg is required to perfuse the brain, kidneys, and coronary arteries; in septic shock, a target MAP of ≥65 mmHg is a core resuscitation endpoint.
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| MAP Value | Interpretation |
|---|---|
| < 60 mmHg | Critical — inadequate organ perfusion (shock) |
| 60–69 mmHg | Low — monitor closely, intervene if symptomatic |
| 70–100 mmHg | Normal — adequate organ perfusion |
| 101–110 mmHg | Elevated — hypertension, monitor |
| > 110 mmHg | Severely elevated — assess for hypertensive urgency/emergency |
Calculated as MAP = (systolic + 2 × diastolic) ÷ 3. The diastolic is weighted twice because the heart spends roughly two-thirds of each cycle in diastole — which is also why a low diastolic pulls the MAP down faster than people expect.
| Blood pressure | MAP | Interpretation |
|---|---|---|
| 120/80 | 93 mmHg | Normal |
| 110/70 | 83 mmHg | Normal |
| 100/60 | 73 mmHg | Adequate perfusion |
| 90/60 | 70 mmHg | Borderline — monitor closely |
| 90/50 | 63 mmHg | Below target — organ perfusion at risk |
| 85/45 | 58 mmHg | Low — intervention usually needed |
| 140/90 | 107 mmHg | Elevated |
| 160/100 | 120 mmHg | High |
The number most often quoted as the floor is 65 mmHg — the MAP generally considered the minimum needed to perfuse the brain, kidneys, and other organs, and the usual target in sepsis and shock resuscitation. Look at the 90/50 row: the systolic still reads 90, which can look acceptable at a glance, yet the MAP has dropped to 63. That gap is exactly why MAP is worth calculating rather than eyeballing the top number.
| Blood pressure | Working | MAP |
|---|---|---|
| 118/76 | (118 + 2 × 76) ÷ 3 = 270 ÷ 3 | 90 mmHg |
| 96/52 | (96 + 2 × 52) ÷ 3 = 200 ÷ 3 | 67 mmHg |
| 84/40 | (84 + 2 × 40) ÷ 3 = 164 ÷ 3 | 55 mmHg |
| 150/95 | (150 + 2 × 95) ÷ 3 = 340 ÷ 3 | 113 mmHg |
The second and third rows are why MAP gets charted in sepsis and after surgery. A systolic of 96 or 84 can pass a quick glance, but with a diastolic of 52 or 40 the MAP sits at 67 and 55. The first is just above the usual floor of 65; the second is well below it.
The Surviving Sepsis Campaign guidelines recommend an initial MAP target of 65 mmHg for adults with septic shock who need vasopressors, rather than a higher target. Much of the evidence comes from the SEPSISPAM trial, which compared a target of 65–70 mmHg with 80–85 mmHg and found no difference in 28-day mortality. The higher target did bring more atrial fibrillation. In patients with long-standing hypertension, the higher target reduced the need for renal replacement therapy. That is one reason targets are individualised: someone whose kidneys are used to a MAP of 110 may not perfuse well at 65.
Outside shock, MAP thresholds come from local protocols and the prescriber. Common examples are post-operative orders, neurosurgical patients and patients on titrated vasoactive drips.
An automated cuff does not calculate MAP from the systolic and diastolic. The oscillometric method works the other way round: the largest pulse oscillation in the cuff corresponds closely to the mean pressure, and the systolic and diastolic values are estimated from it by the device’s algorithm. So the MAP on the monitor is often a few mmHg away from what the formula gives for the same displayed numbers, and the monitor’s figure is the one to chart. An arterial line measures MAP directly as the average of the whole waveform.
The formula is still worth knowing. Manual readings, documentation from another unit and exam questions all give you systolic and diastolic only. The one-third weighting assumes a normal heart rate. At very fast rates diastole shortens, so the true mean drifts up towards the arithmetic average.
Normal MAP is 70–100 mmHg. A MAP below 60 mmHg is considered critically low and indicates inadequate perfusion of vital organs. In clinical practice, a MAP of ≥65 mmHg is the standard target in patients with septic shock receiving vasopressors.
MAP is not simply the average of systolic and diastolic — it is a weighted average that accounts for the fact that the heart spends approximately twice as long in diastole as in systole at normal heart rates. The formula MAP = (SBP + 2 × DBP) ÷ 3 reflects this weighting.
Below 65 mmHg is generally the point at which organ perfusion is at risk, and 65 is the usual resuscitation target in sepsis and shock. Patients with chronic hypertension may need a higher MAP to perfuse adequately, so targets are set individually.
93 mmHg. Using (systolic + 2 × diastolic) ÷ 3: (120 + 160) ÷ 3 = 93 mmHg, comfortably within the normal range of roughly 70–100 mmHg.
Automated oscillometric cuffs measure mean pressure directly, at the point of largest cuff oscillation, and estimate systolic and diastolic from it. The device’s MAP is therefore not derived from the formula and can differ by a few mmHg. Chart the monitor’s value; use the formula when you only have systolic and diastolic.
The Surviving Sepsis Campaign recommends an initial target of 65 mmHg for adults with septic shock on vasopressors. Targets are individualised, and patients with chronic hypertension may need a higher MAP to perfuse their kidneys.