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Anion Gap Calculator

Calculate the serum anion gap to evaluate metabolic acidosis.

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Anion Gap Calculator

Calculate serum anion gap

Complete Guide

Overview

Calculate the serum anion gap to evaluate metabolic acidosis. Use this calculator to get instant, accurate results based on standard health formulas and guidelines.

⚠️This tool is for educational and screening purposes only and is not a substitute for professional medical advice.

How to Use

1

Enter your details in the input fields above.

2

Select your preferred units (metric or imperial) if available.

3

Click the Calculate button to view your instant results and interpretation.

Formula & Calculation

Refer to the in-depth guide below for complete calculation formulas.

Benefits of Using This Calculator

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Accurate Results

Provides instant calculations for anion gap calculator.

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Clear Guidance

Compares your score against standard medical reference ranges.

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Fast & Free

No sign-up required — fast, private calculation on any device.

Pro Tips

  • Enter accurate measurements for the most reliable results.
  • Track your results over time to identify long-term trends.
  • Consult a qualified healthcare professional for medical interpretation.
In-Depth Guide

Anion Gap Calculator: Evaluate Metabolic Acidosis

When the body becomes too acidic, clinicians need to determine why. The anion gap is the first and most important step in this evaluation. It separates high-anion-gap metabolic acidosis — caused by accumulation of unmeasured acids — from normal-anion-gap acidosis, which has a completely different set of causes.

The Formula

Anion Gap = Sodium − (Chloride + Bicarbonate)

Worked Example

Na: 140 | Cl: 100 | HCO3: 15
Anion Gap = 140 − (100 + 15) = 25 mEq/L (High — high anion gap acidosis)

Calculate your anion gap with our Anion Gap Calculator.

Reference Values

Anion GapInterpretation
8–12 mEq/LNormal
Above 12 mEq/LHigh Anion Gap — acid accumulation
Below 8 mEq/LLow Anion Gap — less common, multiple causes

Causes of High Anion Gap Acidosis (MUDPILES)

  • Methanol poisoning
  • Uremia (kidney failure)
  • Diabetic ketoacidosis (DKA)
  • Propylene glycol toxicity
  • Isoniazid / Iron toxicity
  • Lactic acidosis (sepsis, heart failure, liver failure)
  • Ethylene glycol (antifreeze poisoning)
  • Salicylate (aspirin) toxicity

Clinical Importance

The anion gap is used in emergency medicine and ICU settings to rapidly evaluate patients presenting with abnormal blood gas or electrolyte results. It directs the differential diagnosis and guides emergency management of potentially life-threatening conditions like DKA and lactic acidosis.

Final Thoughts

The anion gap is one of the most clinically useful laboratory calculations in acute medicine — a simple subtraction that carries enormous diagnostic weight.

Calculate your anion gap with our free Anion Gap Calculator.

For educational purposes only. Clinical interpretation requires the full clinical picture and should be made by a qualified physician.