Plasma Osmolality Calculator

Your details

Measured serum sodium concentration. Normal range is 136-145 mEq/L.
mEq/L
Fasting serum glucose. Normal fasting range is 70-100 mg/dL (3.9-5.6 mmol/L).
mg/dL
Serum BUN. Normal range is 7-20 mg/dL (2.5-7.1 mmol/L).
mg/dL
Lab-measured serum osmolality by freezing-point depression. Leave at 0 to skip the osmolal gap calculation.
mOsm/kg
Serum ethanol level, used to correct the calculated osmolality before computing the unexplained osmolal gap. Leave at 0 if not applicable.
mg/dL
Calculated OsmolalityNormal
290mOsm/kg

Estimated plasma osmolality via Smithline-Gardner formula

Osmolality StatusNormal (275-295 mOsm/kg)
290 mOsm/kg
Critically Low<265Low265-275Normal275-295Elevated295-320Critically High320+

Calculated osmolality is 290.0 mOsm/kg - Normal (275-295 mOsm/kg).

  • Plasma osmolality is within the normal range (275-295 mOsm/kg). The body maintains this range through ADH secretion and thirst regulation.

Next stepThis result is a screening estimate. Clinical decisions should be based on measured osmolality, full electrolyte panel, and patient context.

 = Powered by OnlyCalculators