Anion Gap Calculator

Written by Great Medico

Updated September 24, 2026 •2 min read

Share Print Save

Fluid and electrolyte decisions often start with a small equation and a careful unit check. Anion Gap Calculator makes that calculation visible without pretending the number replaces bedside assessment.

What this calculator does

Anion Gap Calculator uses Sodium, Chloride, Bicarbonate, Potassium, and Albumin to calculate anion gap. Where supported, it also shows With potassium and Albumin-corrected so the primary result is easier to check. It follows the exact field flow and engine behavior in this plugin rather than describing a different calculator with the same name. Fluid and electrolyte formulas are sensitive to units, timing, ongoing losses, kidney function, and rapidly changing physiology. They are most useful as structured estimates alongside repeat measurements and bedside assessment.

How to use it

Enter or select Sodium, Chloride, Bicarbonate, Potassium, and Albumin. Use the units offered by the calculator and keep paired laboratory or treatment values from the same clinical episode whenever the formula assumes that. If an entry is unknown, do not substitute a guess simply to obtain a number.

How the calculation works

The primary anion gap is sodium − chloride − bicarbonate. The calculator also shows a potassium-inclusive gap by adding potassium and an albumin-corrected gap by adding 2.5 × (4 − albumin) to the potassium-free result.

Example

Using the sample values prefilled in this calculator, the primary result is 12 mmol/L (Anion gap), With potassium is 16 mmol/L, and Albumin-corrected is 12 mmol/L. This example demonstrates the plugin’s own calculation path; replace the sample inputs with verified values before interpreting a real result.

How to interpret the result

Interpret the gap using the laboratory’s reference range and albumin context. A raised or normal gap narrows possibilities but does not identify the cause of acidosis by itself.

Limitations and notes

Fluid and electrolyte formulas are sensitive to units, timing, ongoing losses, kidney function, and rapidly changing physiology. They are most useful as structured estimates alongside repeat measurements and bedside assessment. During active treatment, repeat laboratory measurements and clinical response can rapidly make an earlier calculated estimate outdated.