Mean arterial pressure calculator

How is mean arterial pressure calculated?

MAP ≈ diastolic + (systolic − diastolic) ÷ 3. For 120/80, that is 80 + 40 ÷ 3 = 93.3 mm Hg.

Why is it not the simple average?

The heart spends about twice as long relaxing (diastole) as contracting, so the diastolic pressure counts more.

What MAP is needed for the organs?

StatPearls notes that perfusing vital organs requires maintaining a MAP of at least 60 mm Hg.

What is pulse pressure?

Systolic minus diastolic — 40 mm Hg for 120/80.

Is this an exact measurement?

No — it is an estimate from two numbers. Hospitals can measure MAP directly with an arterial line.

Worked example: two blood pressures

For 140/90 the pulse pressure is 140 − 90 = 50. One third of that is 16.7, and 106.7 mm Hg is 90 + 16.7. For 90/60 the pulse pressure is 30, one third is 10, and the MAP is 70 mm Hg. The same result comes from (systolic + 2 × diastolic) ÷ 3, which is the form some textbooks use: (140 + 2 × 90) ÷ 3 = 106.7. The plain average of 140 and 90 would be 115, far above the MAP, which shows how much weight the longer diastolic phase carries.

What MAP do doctors aim for?

It depends on the situation. For adults in septic shock who need vasopressor drugs, the 2021 Surviving Sepsis Campaign guidelines recommend an initial target MAP of 65 mm Hg rather than a higher target (a strong recommendation based on moderate-quality evidence). That is a critical-care target set and adjusted by a care team, not a goal for a home cuff reading.

How good is the one-third rule?

It is the traditional estimate, not the only one. In a 2016 study of 1,878 people in Hypertension Research, the authors compared seven ways of calculating MAP and found that diastolic pressure plus 0.412 times the pulse pressure tracked carotid wall thickening, aortic stiffness and left ventricular mass more closely than the traditional 0.33. They add that estimates still need comparing with direct arterial measurements. The calculator uses the traditional 1/3 because that is the form most references and clinical tools quote.

Common mistakes with MAP

Entering the numbers the wrong way round: if the diastolic value is higher than the systolic one, as in 80 over 120 here, the calculator returns no result, since the pulse pressure would be negative. Taking the plain average of the two numbers. Reading a home cuff MAP as if it were an arterial-line value from the hospital. Mixing units: blood pressure here is in mm Hg, so values in kPa must be converted first. And treating MAP as a blood pressure category: categories such as normal, elevated or stage 1 hypertension are defined by systolic and diastolic readings, not by MAP.

Sources and related calculators

Sources: StatPearls, “Physiology, Mean Arterial Pressure”; L. Evans et al., “Surviving Sepsis Campaign: International Guidelines for Management of Sepsis and Septic Shock 2021,” recommendation on the initial MAP target; T. G. Papaioannou et al., “Mean arterial pressure values calculated using seven different methods and their associations with target organ deterioration in a single-center study of 1878 individuals,” Hypertension Research (2016). Related: blood pressure calculator, target heart rate calculator and IV drip rate calculator.

For general information only — not medical advice. Talk with your doctor or another health professional about your own health. How we check our calculators.