Loading calculators...
Fetching calculator categories and tools for this section.
Preparing tools and content for you. This usually takes a second.
Fetching calculator categories and tools for this section.
Calculate serum anion gap from BMP-style sodium, chloride, and bicarbonate: classic AG, optional potassium-inclusive gap, and albumin-corrected AG for hypoalbuminemia. Includes HAGMA vs NAGMA teaching and delta gap guidance — for education, not diagnosis. Pair with osmolality and GFR tools on the medical hub.
Last updated: June 4, 2026
Classic anion gap
12 mEq/L
Na⁺ − (Cl⁻ + HCO₃⁻)
Not a substitute for clinical judgment
Reference intervals vary by laboratory and patient context. This tool performs arithmetic only and does not diagnose acid–base disorders.
Na 140, Cl 104, HCO₃ 24 mEq/L
AG = 12 mEq/L
Na 139, Cl 100, HCO₃ 15
AG ≈ 24 mEq/L
Confirm with pH, lactate/ketones, context
| Name | Formula | Notes |
|---|---|---|
| Classic anion gap | AG = Na⁺ − Cl⁻ − HCO₃⁻ | Most common BMP teaching form (mEq/L) |
| With potassium | AG = (Na⁺ + K⁺) − Cl⁻ − HCO₃⁻ | Optional; K⁺ is small but included when entered |
| Albumin-corrected | AG_corr = AG + 2.5 × (4.0 − albumin [g/dL]) | Reference albumin 4.0 g/dL; coefficients vary in literature |
After calculating AG above, some clinicians estimate mixed metabolic disorders:
Measured AG 8 mEq/L with albumin 2 g/dL (reference 4.0):
AG_corr = 8 + 2.5 × (4.0 − 2) = 13 mEq/L
Without correction, HAGMA can be underestimated in critically ill or cirrhotic patients.
Not medical advice. Acid–base treatment requires blood gas, repeat labs, and clinician judgment. Life-threatening acidosis or suspected ingestion needs emergency care.
For medical students, residents, and lab medicine teaching
Suggested hashtags: #Medicine #LabMedicine #AcidBase #Education #Calculator