Anion Gap Calculator
Calculate the anion gap to evaluate metabolic acidosis. Uses serum sodium, chloride, and bicarbonate levels.
Published by:
isCalculator Editorial Team
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How to use this tool?
How to Use the Anion Gap Calculator
- Enter the values for Sodium (Na+), Chloride (Cl-), and Bicarbonate (HCO3-) in mEq/L. All fields are required and must be positive numbers (decimals allowed).
- Click "Calculate Anion Gap" to compute the result.
- Interpret the result:
- < 3 mEq/L – Low anion gap (possible hypoalbuminemia, myeloma, etc.)
- 3–11 mEq/L – Normal anion gap (no metabolic acidosis)
- > 11 mEq/L – High anion gap (possible metabolic acidosis)
- Formula used: Na+ - (Cl- + HCO3-). The result is rounded to one decimal place.
Note: All values must be in mEq/L. If any input is invalid or negative, an error will appear.
Previous Results
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Frequently Asked Questions
The anion gap is a calculated value that helps differentiate types of metabolic acidosis. It represents the difference between measured cations (sodium) and measured anions (chloride and bicarbonate).
The normal anion gap is typically 3-11 mEq/L, but reference ranges may vary slightly by laboratory.
A high anion gap (>11 mEq/L) suggests the presence of unmeasured anions, often due to metabolic acidosis from conditions like diabetic ketoacidosis, lactic acidosis, or uremia.
