Clinical Calculators

Mean Arterial Pressure (MAP)

Estimates mean arterial pressure from systolic and diastolic blood pressure as (systolic + 2 × diastolic) ÷ 3

2 items left

50 to 250
mmHg
30 to 150
mmHg

Formula

  • Mean arterial pressure (MAP) = (systolic blood pressure + 2 × diastolic blood pressure) ÷ 3. This equals the diastolic pressure plus one third of the pulse pressure (systolic minus diastolic)
  • When an arterial catheter or monitor measures the mean arterial pressure, use the measured value. This formula is an estimate for when it cannot be measured

Cautions

  • An estimate calculated from the systolic and diastolic pressures. When arterial pressure can be measured (an arterial catheter, or an automatic oscillometric device), prefer the measured value.
  • The "one third" is a rough share of the pulse pressure that is added to the mean. In a study of the brachial artery in 1,927 adults aged 35 to 55, the measured share was about 42% (men 41%, women 44%), and the one-third (33%) formula estimated the mean arterial pressure lower than the measured value. The share also changes with the artery (brachial, radial and carotid values differ) and with sex (higher in women).
  • For the initial resuscitation of sepsis, a mean arterial pressure target of 65 mmHg is weakly recommended (Japanese Clinical Practice Guidelines for Management of Sepsis and Septic Shock 2024; the recommendation is weak and the certainty of evidence is low). Septic shock is diagnosed, in addition to meeting the diagnostic criteria for sepsis, when a vasopressor is needed in addition to fluids to keep the mean arterial pressure at 65 mmHg or higher and the lactate is above 2 mmol/L. Targets for other conditions are not covered by this tool.
  • No interpretation bands are given. Interpret the value together with the condition, any chronic hypertension, and the signs of organ perfusion.
  • The calculation also runs when the diastolic pressure is higher than the systolic pressure. Check that the measurement or the entry was not mixed up.

References

  1. Special Committee of the Japanese Clinical Practice Guidelines for Management of Sepsis and Septic Shock 2024. Japanese Clinical Practice Guidelines for Management of Sepsis and Septic Shock 2024 (J-SSCG 2024) (in Japanese). J Jpn Soc Intensive Care Med. 2024;31(Suppl 2). Published 25 December 2024. (List of CQs: CQ1-2 (p. S1172) and CQ3-3 (p. S1231); note f to the Phoenix Sepsis Score table (p. S1299)) https://www.jsicm.org/pdf/cq/J-SSCG2024/J-SSCG2024_Main.pdf[Guideline]
  2. Mahieu D, Rietzschel E, De Buyzere M, Gillebert T, Segers P, Van Bortel L. Validity of the one-third rule to calculate mean arterial pressure. Artery Res. 2007;1(2):71. (Abstract (P.081)) DOI: 10.1016/j.artres.2007.07.015[Review article]
  3. (Systolic blood pressure + 2 × diastolic blood pressure) ÷ 3 = diastolic blood pressure + (systolic blood pressure - diastolic blood pressure) ÷ 3. A rewriting of the formula that adds one third of the pulse pressure to the diastolic pressure.[Derivation]

Checked on: 2026-10-15

Disclaimer

This calculation is intended to support the judgment of healthcare professionals. Results are for reference only; decisions about diagnosis and treatment must be made by the responsible healthcare professional. The values you enter never leave your device.