Serum Osmolarity Calculator

The Serum Osmolarity Calculator estimates your blood's solute concentration based on Sodium, Glucose, and Blood Urea Nitrogen levels. This tool helps patients and healthcare providers quickly assess fluid balance and hydration status. Whether you are interpreting blood test results, managing diabetes, or monitoring kidney function, this calculator provides instant insights into your metabolic health.

Range: 120-160 mEq/L
Range: 50-400 mg/dL
Range: 5-50 mg/dL

How Serum Osmolarity Is Calculated

Serum osmolarity measures the concentration of dissolved particles in your blood, which controls how water moves in and out of your cells.

Osmolarity = (2 × Sodium) + (Glucose ÷ 18) + (BUN ÷ 2.8)

Where:

  • Sodium, Glucose, and BUN are input values from your blood test.
  1. First, the sodium level is doubled because it separates into two particles in the blood and has the largest effect on the result.
  2. Next, glucose is divided by 18 and BUN is divided by 2.8 to convert them into the correct units.
  3. Finally, these three values are added together to get your total serum osmolarity.

This calculation follows standard medical guidelines to provide a reliable estimate of your fluid status without needing a specialized lab machine.

What Your Serum Osmolarity Means

This number tells you if your body has the right balance of water and dissolved particles like salt and sugar.

  • Normal Results (275-295 mOsm/kg): Your fluid levels are balanced. Keep up your current hydration and eating habits to stay healthy.
  • High Results (Over 295 mOsm/kg): You might be dehydrated or have high glucose. Drink water and seek medical advice if the number does not go down.
  • Low Results (Under 275 mOsm/kg): You may have too much water in your body. Limit fluid intake and talk to a doctor about your electrolyte levels.

Important Note

This calculator is for informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.

Track your results over time to see how your diet and health habits affect your fluid balance.