The Osmolality Lab™ looks forward to working with and supporting you! Visit our Resources Page for abstracts, articles, and osmolality basics. A handy glossary is included for quick reference on key terms related to our core testing services.

The Basics of Osmolality


The concentration of a solution expressed as the total number of solute particles (osmoles) per kilogram of solvent. When solutes are added to a pure solvent the resulting solution differs from the pure solvent in several ways including freezing point, boiling point, vapor pressure, and osmotic pressure.

The change in these characteristics is not proportional to weight, size or shape of the added solutes, resulting in the importance of osmolality in determining the concentration of solutes.

Osmolality Equation:

Osmolality is the number of Osmols of solute particles per kilogram of the pure solvent. As most ionic species do not completely dissociate, osmolality is a unit of concentration, which takes into account the dissociative effect. Osmolality is usually expressed in mOsm/kg H20. One milliosmol (mOsm) is 10-3 osmols. The osmolality equation is:

Osmolality = ΦnC = osmol / kg H20


Φ = osmotic coefficient, which accounts for the degree of molecular dissociation

n = number of particles into which a particle can dissociate

C = molal concentration of the solution

Literature, Abstracts, and News

• “Electrolytes: Definition, Functions, Imbalance and Sources”

• “Fluid and Electrolyte Balance”

• “The Effects of Sports Drink Osmolality on Fluid Intake and Immunoendocrine Responses to Cycling in Hot Conditions”

• “Osmolality of Frequently Consumed Beverages”

• “Scientific opinion on the substantiation of health claims”

• “Mucosal irritation potential of personal lubricants relates to product osmolality…”

• “Use and procurement of additional lubricants for male and female condoms: WHO/UNFPA/FHI360”;jsessionid=2037C017D6AD5ADE175A3E2FEE01A515?sequence=1

• “Vaginal hygiene products like sprays, wipes, creams linked to infections: study”

• “Osmolality and pH Properties of Some Commercial Lubricants”

• “Global Consultation on Personal Lubricants”

• “FDA warns manufacturers of products labeled as homeopathic for putting consumers at risk with significant violations of manufacturing quality standards…”

• “Statement from FDA: transformative new steps to modernize FDA’s 510(k) program…”

• “Beverage Osmolality as a marker for maintaining appropriate body hydration”

Other Forms


Osmolality (Vapor Pressure)

Osmolality (Freezing Point)

pH Test

Viscosity Test

Conductivity Test

Free-Chlorine Test

Total Chlorine Test

TDS Test

Salinity Test

Scroll to Top