Anion gap calculator
Work out your serum anion gap from three electrolytes on a metabolic panel — sodium, chloride, and bicarbonate (CO₂) — plus an optional albumin-corrected value. The anion gap helps sort out acid–base problems. Values are in mEq/L (the same as mmol/L for these ions).
Your privacy: this calculator runs entirely in your browser — nothing you type is sent anywhere. It's the same on-device principle Quanome is built on.
Educational reference only — not medical advice. The anion gap is a signpost for acid–base problems, read with bicarbonate, pH, and the clinical picture — not a diagnosis on its own. Reference ranges vary by lab and analyser.
## What anion gap numbers mean
| Anion gap (Na − (Cl + HCO₃)) | Category |
| --- | --- |
| < 8 mEq/L | Low (uncommon; e.g. low albumin, lab effects) |
| 8–12 mEq/L | Normal (classic range; some analysers 3–11) |
| > 12 mEq/L | High (high-anion-gap metabolic acidosis) |
A **high** gap suggests unmeasured acids — lactate, ketones, kidney failure, or toxins (the teaching mnemonic **MUDPILES**). A **low** gap is uncommon and often reflects a low albumin. Because ranges differ between labs, read your value against the one on your own report.
## The formula
- **Anion gap = Na − (Cl + HCO₃)** — the common potassium-free version used here.
- **With potassium:** some labs use Na + K − (Cl + HCO₃), which raises the normal range by about 4 mEq/L.
- **Albumin-corrected anion gap = anion gap + 2.5 × (4.0 − albumin g/dL).** Albumin is an anion, so a low albumin lowers the measured gap and can mask an acidosis — enter an albumin to see the corrected value. If albumin is normal (4.0 g/dL), the correction is zero.
## The rest of your metabolic panel
The anion gap is built from your electrolytes — read each on its own too:
- **Sodium** — see [what your sodium level means](/blog/what-your-sodium-level-means/).
- **Chloride** — see [what your chloride blood test means](/blog/what-your-chloride-blood-test-means/).
- **Bicarbonate (CO₂)** — see [what your CO₂ (bicarbonate) blood test means](/blog/what-your-co2-blood-test-means/).
- **Calcium & albumin** — on the same panel; correct calcium for albumin with the [corrected calcium calculator](/tools/corrected-calcium-calculator/).
## Track your labs over time — privately
A single anion gap is a snapshot; the value is in the **trend**. [Quanome](/) pulls your labs, Apple Health, and even your DNA into one private timeline on your device — parsed locally, never uploaded — with an AI coach that reads your metabolic panel in whichever units you use.
Track your labs over time, privately
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