Osmolar Gap
Difference between measured and calculated osmolality.
What is Osmolar Gap?
Difference between measured and calculated osmolality. Osmolar Gap is intended for use in: Adults.
How to Use the Osmolar Gap Calculator
- Enter Measured osmolality in mOsm/kg.
- Enter Sodium in mEq/L.
- Enter Glucose in mg/dL.
- Enter BUN in mg/dL.
- Click Calculate to see your result and interpretation.
Formula & Version
This calculator uses formula version 1.0, last reviewed September 2026.
Clinical Considerations & Limitations
- A normal osmolar gap does NOT rule out toxic alcohol ingestion, especially later after ingestion once the parent alcohol has been metabolized.
References
- Standard toxicology calculation: Osmolar Gap = Measured − Calculated Osmolality; gap > 10 is generally considered abnormal
Frequently Asked Questions
What is Osmolar Gap?
Difference between measured and calculated osmolality.
Who is Osmolar Gap intended for?
Adults. Always confirm applicability to your specific patient before use.
What are the limitations of Osmolar Gap?
A normal osmolar gap does NOT rule out toxic alcohol ingestion, especially later after ingestion once the parent alcohol has been metabolized.
What formula or reference does Osmolar Gap use?
Standard toxicology calculation: Osmolar Gap = Measured − Calculated Osmolality; gap > 10 is generally considered abnormal
Is Osmolar Gap a diagnosis?
No. Osmolar Gap produces a score or estimate to support clinical decision-making — it is not a diagnosis and should be interpreted alongside full clinical judgement.
