This version was machine-translated from German and has not been medically reviewed. The authoritative version is the German version.
Winter's formula
Expected pCO₂ in metabolic acidosis: 1.5 × HCO₃ + 8 ± 2
Scientific basis
Reference range of your own laboratory
Anion gap and delta ratio depend on the measurement method for sodium and chloride. The reference values used here (AG 12, HCO₃⁻ 24) are conventions of the cited papers; your own laboratory's reference range takes precedence.
Calculation aid for healthcare professionals: the calculator reproduces what the sources cited assign to the inputs. Clinical assessment and every treatment decision remain with the treating physician. Inputs and results are not stored.
Frequently asked questions
Winter's formula: What does this calculator compute?
Calculates by the Winter formula (Albert, Dell & Winters 1967) the pCO₂ expected in metabolic acidosis (1.5 × HCO₃ + 8 ± 2 mmHg) and compares it with the measured value – to detect an additional respiratory disorder.
Winter's formula: Which sources is this calculator based on?
Kraut JA, Madias NE: Serum anion gap: its uses and limitations in clinical medicine (Clin J Am Soc Nephrol 2:162–174) (2007); Figge J, Jabor A, Kazda A, Fencl V: Anion gap and hypoalbuminemia (Crit Care Med 26:1807–1810) (1998); Wrenn K: The delta (Δ) gap: an approach to mixed acid-base disorders (Ann Emerg Med 19:1310–1313) (1990); Albert MS, Dell RB, Winters RW: Quantitative displacement of acid-base equilibrium in metabolic acidosis (Ann Intern Med 66:312–322) – “Winter formula” (1967); Berend K, de Vries AP, Gans RO: Physiological approach to assessment of acid-base disturbances (N Engl J Med 371:1434–1445) – Table 2: Expected compensatory responses (2014); Kraut JA, Madias NE: Metabolic acidosis: pathophysiology, diagnosis and management (Nat Rev Nephrol 6:274–285) (2010)