Choose the concentration definition first
Concentration can mean several different ratios. This calculator separates molarity, mass concentration, mass percent, and volume percent so quantities from incompatible definitions are not placed in one formula. Choose the form requested by the problem, then enter only the matching numerator and denominator. The result names its definition and unit instead of returning an unexplained percentage or decimal.
Molarity uses moles per litre of final solution. Mass concentration uses grams of solute per litre of final solution. Mass percent compares component mass with total solution mass, while volume percent compares component volume with final solution volume. These values may describe the same sample differently, but converting between them requires additional information such as molar mass or density.
Calculate molarity or mass concentration
For molarity, enter solute moles and final solution volume. Volume is converted from millilitres when necessary before c = n/V is applied. For example, 0.5 mol in 2 L gives 0.25 mol/L. Use final solution volume after preparation, not the starting solvent volume, because dissolved material can change the total volume.
For mass concentration, enter solute mass and final solution volume. Mass is converted to grams and volume to litres before dividing. Ten grams in 0.5 L gives 20 g/L. This is not automatically 20 mol/L; molarity also requires the solute molar mass. Keep the chemical identity and mass unit with any source measurement.
Calculate mass percent or volume percent
Mass percent is component mass divided by total solution mass times 100. Ten grams of component in 200 grams total gives 5% m/m. Both numbers must use the same mass unit, and component mass cannot exceed total mass. The denominator includes every component, not only the solvent and not an unrelated starting batch mass.
Volume percent is component volume divided by final solution volume times 100. Twenty-five millilitres in 500 millilitres final volume gives 5% v/v. Both values must use the same volume unit, and component volume cannot exceed final volume. Real liquids may not have perfectly additive volumes, so follow the stated final-volume preparation method.
Check units and reverse the ratio
Multiply molarity or mass concentration by final litres to recover the entered moles or grams. Multiply a percentage by the denominator and divide by 100 to recover component amount. These reverse checks confirm both arithmetic and unit selection. A percentage must remain between zero and 100 under the definitions provided here.
Do not compare concentration numbers without their units and basis. A result of 5% m/m, 5% v/v, 5 g/L, and 5 mol/L represents four different statements. Density can relate mass and volume, while molar mass can relate grams and moles, but neither is assumed on this page. Select a dedicated conversion only when those additional values are known.
Scope and private calculation
The calculator does not infer density, molar mass, purity, solution contraction, dissociation, temperature effects, or regulatory meaning. It calculates one selected concentration definition from compatible inputs. Use measured final quantities and appropriate significant figures for laboratory work, and consult authoritative guidance before interpreting a concentration as safe or effective.
The values are calculated in the current browser tab. NexaCurrent does not upload the quantities, formulas, chemical names, element choices, or other information entered here, and no account is needed. Copying is a deliberate action after the answer and working are visible. Refreshing or leaving the page clears the current calculation, so keep a copied result if it is needed for later study.