Mass/Volume Percent Calculator

At a glance:Mass/volume percent (w/v%, or %(m/v)) is a mixed concentration notation defined as 'the ratio of solute mass (g) to solution volume (mL) times 100': w/v% = (solute mass g / solution volume mL) × 100. It answers 'how many grams of solute are in 100 mL of solution' — so numerically w/v% equals 'grams per 100 mL' (g/100 mL). This notation is common because in lab and medical preparation we usually 'weigh the solid solute (by balance, in g)' and then 'make up to a volume (in mL)', combining the convenience of mass and volume. Using this tool's default: dissolve 9 g solute and make up to 1000 mL, w/v% = (9 / 1000) × 100 = 0.9% — exactly the most common clinical '0.9% normal saline', i.e. 0.9 g NaCl per 100 mL. w/v% is everywhere in medicine and biology: IV normal saline (0.9% NaCl), dextrose injection (5% glucose, 5 g per 100 mL), disinfection and cleaning solutions, cell-culture and biochemical buffers are mostly labelled in w/v%. It is also used in agriculture (pesticide, fertiliser solutions), food (additive concentration) and industrial formulations. Comparing w/v% with other notations: mass percent w/w% (solute mass / solution mass × 100) for solid–solid or mass-ratio needs; volume percent v/v% (solute volume / solution volume × 100) for liquid–liquid mixing (e.g. alcohol); molarity mol/L for stoichiometric calculation. To convert between w/v% and molarity you need the solute molar mass: molarity (mol/L) = (w/v% × 10) / molar mass. Notes on using w/v%: first, fix the units — solute mass in grams (g), solution volume in millilitres (mL), so the computed w/v% equals the conventional g/100 mL; convert if other units are used. Second, the volume is the 'final total solution volume (after making up)', not the volume of solvent added — prepare by dissolving the solute and making up to the mark, not by measuring solvent first then adding solute. Third, strictly w/v% is not dimensionless (it is g/mL times 100) but is conventionally written as a percent. Fourth, volume changes with temperature, so precise preparation should mind temperature. Fifth, this calculator takes a non-negative solute mass and a solution volume > 0. In short, this calculator lets you quickly compute the mass/volume percent from solute mass and solution volume — a practical tool for medical preparation, lab solution prep and concentration labelling.