Plasma Osmolality

Calculate Plasma Osmolality instantly with the exact formula and a worked example.

Plasma Osmolality

Na
Glucose, mg/dL
BUN, mg/dL
Osm
290.5556mOsm/kg
Calculate Plasma Osmolality instantly with the exact formula and a worked example.

More about: Plasma Osmolality

What it calculates

The “Plasma Osmolality” calculator computes Osm in mOsm/kg from 3 parameters: na, glucose, mg/dl, bun, mg/dl.

Used by professionals and patients to assess health metrics, dosages, and risks.

Example calculation

With parameters Na = 140, Glucose, mg/dL = 100, BUN, mg/dL = 14 the result is 290.56 mOsm/kg.

How to use

  1. Enter na, glucose, mg/dl and bun, mg/dl — each field above is adjustable with a slider.
  2. Osm (mOsm/kg) is calculated automatically as you type.
  3. Check the worked example below to see the formula applied to real numbers.
  4. Copy the result or bookmark this calculator.

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FAQ

How is BMI calculated?
BMI = weight (kg) / height (m)². Example: 70 kg / (1.75 m)² = 22.9. The WHO normal range is 18.5–24.9; below that is underweight, 25–29.9 is overweight, and 30+ is obese.
Is BMI accurate for everyone?
No. BMI does not distinguish muscle from fat, so athletes may show a high BMI with low body fat. It is also less reliable for teenagers, pregnant people, older adults, and very tall or short individuals.
What are the BMI categories?
Underweight: below 18.5. Normal: 18.5–24.9. Overweight: 25–29.9. Obese class I: 30–34.9; class II: 35–39.9; class III: 40+.
What is a better measure than BMI?
Body fat percentage, waist-to-height ratio (aim for under 0.5), and waist circumference give a clearer picture of health than BMI alone.

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