A raised anion gap points toward causes such as ketoacidosis, lactic acidosis or toxins.
How to use the Anion Gap Calculator
- Sodium
- Chloride
- Bicarbonate
- Albumin
Results update as you type, and every field accepts the units shown in its menu.
How it works
Subtract chloride and bicarbonate from sodium. Low albumin lowers the gap, so a correction is added.
Inputs explained
| Field | What to enter |
|---|---|
| Sodium | In mEq/L |
| Chloride | In mEq/L |
| Bicarbonate | In mEq/L |
| Albumin | In g/dL |
What each result means
- Anion gap = [Sodium] – ([Chloride] + [Bicarbonate])
- Albumin-corrected anion gap = [Anion gap] + 2.5×(4 – [Albumin])
Health note: this calculator is for education and screening only and is not a diagnosis or treatment advice. Discuss your results with a qualified clinician.
Formula
Anion gap = Na⁺ − (Cl⁻ + HCO₃⁻)Albumin-corrected AG = AG + 2.5 × (4.0 − albumin g/dL)Worked example
Inputs — Sodium: 140 mEq/L; Chloride: 104 mEq/L; Bicarbonate: 24 mEq/L; Albumin: 4 g/dL.
Results — Anion gap = 12 mEq/L; Albumin-corrected anion gap = 12 mEq/L.
Frequently asked questions
What is a normal anion gap?
Commonly about 3–12 mEq/L without potassium, but ranges vary between laboratories.
Should potassium be included?
Some labs add potassium, which raises the normal range by about 4.
What formula does the Anion Gap Calculator use?
Anion gap = Na⁺ − (Cl⁻ + HCO₃⁻).