Molality (m) is moles of solute per kilogram of solvent — not per liter of solution like molarity. Because it is based on solvent mass, molality stays nearly constant when temperature changes, which makes it the preferred unit for colligative properties (boiling point elevation, freezing point depression, and osmotic pressure). The core relation is m = n / kg_solvent. This calculator finds molality from moles and solvent mass, from dissolved grams and a chemical formula, or solves for moles, solvent mass, or solute mass. Use kilograms or grams for solvent; everything runs instantly in your browser.
Molality calculator free — find mol/kg from moles and solvent mass. Convert grams to molality using formula lookup. Chemistry in your browser.
Unlike molarity (mol/L of solution), molality uses kilograms of solvent only and does not change much with temperature. For volume-based concentration, use the Molarity Calculator.
