Note: density defaults to 1.00 g/mL (pure water). For concentrated solutions, adjust accordingly.

This concentration converter handles the most common units used in chemistry, biochemistry, environmental science, and clinical settings. It converts between molar units (M, mM, µM, nM), mass-per-volume units (g/L, mg/dL), percentage units (% w/v, % w/w), and trace concentration units (ppm, ppb, ppt). Because converting between molar and mass-based units requires knowing the molecular weight of the solute, a molar mass input is provided. Conversions involving weight-per-weight units (such as % w/w and ppm w/w) additionally require solution density, which defaults to 1.00 g/mL for dilute aqueous solutions. Common use cases include preparing laboratory solutions, interpreting clinical lab results (e.g. mg/dL for blood glucose), and converting environmental contaminant levels between regulatory reporting units.