Anion Gap & Winters' Formula Calculator

Compute the serum anion gap and the expected respiratory compensation (Winters' formula) in metabolic acidosis from sodium, chloride and bicarbonate.

Sodium Na⁺ (mmol/L)

Chloride Cl⁻ (mmol/L)

Bicarbonate HCO₃⁻ (mmol/L)

How to Use the Anion Gap & Winters' Formula Calculator

Enter serum sodium in mmol/L.
Enter serum chloride in mmol/L.
Enter serum bicarbonate in mmol/L.
Click Calculate to see anion gap and expected pCO₂.

使用场景

•Intensive care acid–base workup.
•Internal medicine teaching rounds.
•Toxicology screening (AG acidosis causes).

公式

Anion gap = Na − (Cl + HCO₃), normal 8–12 mmol/L. Winters: expected pCO₂ = 1.5 × HCO₃ + 8 (±2 mmHg).

常见问题

Should I correct anion gap for albumin?

Yes in hypoalbuminemia — add roughly 2.5 mmol/L per 10 g/L drop below 40 g/L. Uncorrected gap can mask a real high-gap acidosis.

When does Winters' formula apply?

Only in primary metabolic acidosis. If measured pCO₂ is outside expected range, suspect a mixed disorder (respiratory acidosis or alkalosis overlaid).

Medical disclaimer

Educational only. Acid-base interpretation must be done alongside full clinical and laboratory context by a qualified clinician.