Enter mass, volume, and molar mass — get all concentration units.
Solution concentration can be expressed in many ways: Molarity (M) = mol/L — most common in chemistry; g/L or mg/mL — mass concentration; w/v% = g per 100 mL; ppm = mg/L = mg/kg for dilute solutions; molality (m) = mol/kg solvent; normality (N) = equivalents/L. Converting requires molar mass (M↔g/L), density (molarity↔molality), or both. For dilute aqueous solutions at room temperature, 1 ppm ≈ 1 mg/L since water density ≈ 1 g/mL. Choosing the right unit depends on context: molarity for reactions and titrations, w/v% for clinical preparations, ppm for environmental water quality, and molality for colligative properties.