Serum Osmolality Calculator
Blood concentration from sodium, glucose and BUN.
Your result
Normal serum osmolality is 275–295 mOsm/kg. Higher values suggest dehydration; lower values suggest water excess.
Medical disclaimer: This tool is for education and is not medical advice. Read more.
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Frequently asked questions
What does the Serum Osmolality Calculator do?
Blood concentration from sodium, glucose and BUN. Enter your values and the result and chart update instantly.
How accurate is it?
It uses published, widely used formulas. Results are estimates for education and planning, not a diagnosis. Talk to a qualified clinician about decisions affecting your health.
Is my information stored or shared?
No. All calculations run in your browser and nothing you type is sent to a server or saved.
What can I search to find this tool?
People find it by searching for: dehydration lab test; osmolarity calculation; hypernatremia.