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Expected PaCO₂ in metabolic acidosis: Winter's formula

Acid-base & electrolytes

Checks whether respiratory compensation is appropriate. A measured PaCO₂ outside the expected range means a second, respiratory disorder.

What you enter

  • Bicarbonate (mmol/L)
  • Measured PaCO₂ (mmHg or kPa)
FORMULAExpected PaCO₂ (mmHg) = 1.5 × HCO₃ + 8 ± 2
SourceAlbert MS, Dell RB, Winters RW. Quantitative displacement of acid-base equilibrium in metabolic acidosis. Ann Intern Med 1967;66:312-22ReviewedFormula and thresholds checked against the source on 2026-08-22. If the source updates, this line will say so.