millimolar

Millimolar (mM) is a unit of concentration used in chemistry and biology. It represents one thousandth of a mole of solute per liter of solution. Since molarity is defined as moles per liter, millimolar is simply the same unit scaled by 10^-3, so 1 mM equals 1×10^-3 mol/L.

Converting between molarity and millimolar is straightforward: 1 M equals 1000 mM, and 1 mM equals 0.001 M. Values expressed in millimolar are commonly used in laboratories for preparing solutions, buffers, and assay reagents. In dilute aqueous solutions, millimolar concentrations are a practical scale because many biological and chemical processes occur within that range.

Examples help illustrate the unit: a solution with 0.5 mM concentration contains 0.0005 moles of solute per liter. A 10 mM glucose solution contains 0.01 moles of glucose per liter. In practice, researchers often prepare stock solutions at higher concentrations in M or mM and dilute them to the desired working concentration. The millimolar prefix is part of the metric system and is consistent with SI units used for expressing chemical concentrations.