Osmolarity Calculator
Determine the osmotic concentration (osmoles of solute particles per liter of solution) and evaluate solution tonicity relative to standard physiological ranges.
Solute Properties
Input concentration values and ionization properties.
* Represents how many particles a solute splits into in solution (e.g. Glucose = 1, NaCl = 2, MgCl₂ = 3).
Calculated Osmolarity
* Tonicity status: Isotonic (vs blood plasma).
Expert Tip
Standard human blood plasma has an osmolarity range of 280-300 mOsm/L. Solutions below this range are hypotonic (risk of cell swelling), while solutions above are hypertonic (risk of cell shrinking).
Methodology & Equations
Osmolarity Calculation
Osmolarity measures the total concentration of osmotic particles in a liquid medium, multiplying chemical concentration by solute dissociation:
Dissociation & Tonicity
- Tonicity: Measures the effective osmotic pressure gradient across cell membranes. Highly important for preparing physiological cell saline formulations.
- Ion dissociation: Polar solutes like salts break down into ions in solution, whereas covalent solutes like glucose do not dissociate ($i = 1$).
How to Calculate Solution Osmolarity
Osmolarity measures the concentration of solute particles per liter of solution:
Determine Molar Concentration (M)
Find the molarity of the dissolved solute.
Determine the Dissociation Factor (g)
Find the number of particles the compound dissociates into. For covalent solutes like Glucose, g = 1. For ionic compounds like NaCl, g = 2 (dissociates into Na+ and Cl-).
Calculate Osmolarity
Multiply Molarity by the dissociation factor: Osmolarity (Osm/L) = Molarity × g.
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