Venous Blood pH Calculator

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Choose whether you want to estimate venous pH from HCO3/PvCO2, or do a full VBG interpretation including acid-base classification.
Measured serum or venous bicarbonate concentration. Normal venous range: 22 to 29 mEq/L. mEq/L is numerically equal to mmol/L.
mEq/L
Partial pressure of CO2 in venous blood. Normal peripheral venous range: 41 to 51 mmHg (equal in value to torr).
mmHg
Venous blood pHNormal
7.329

Estimated from the Henderson-Hasselbalch equation: 6.1 + log10(HCO3 / (0.0308 x PvCO2))

pH statusNormal venous pH (7.31-7.41)
Estimated arterial pH7.359
Estimated arterial PaCO241mmHg
Estimated arterial HCO322.5mEq/L
Dissolved CO2 content1.417mmol/L
HCO3/CO2 ratio16.94
7.329
Severe acidosis<7.1Acidosis7.1-7.31Normal7.31-7.41Alkalosis7.41-7.55Severe alkalosis7.55+

Venous pH is 7.329 (normal).

  • Venous pH of 7.329 falls within the normal range (7.31-7.41).
  • The estimated arterial pH is approximately 7.359 (venous pH + 0.03 population-average offset). Confirm with an arterial blood gas when precision matters.

Next stepVBG does not assess oxygenation. For definitive acid-base diagnosis, compensatory pattern verification, or oxygenation data, an arterial blood gas (ABG) is required. Always interpret in the clinical context.

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