Percentage Concentration to Molarity Calculator

01 Set up your calculation

1. Choose the direction of conversion.
2. Enter mass percentage or molarity as appropriate.
3. Supply the density of the whole solution and the solute’s molar mass.

02 The relationship

For the assumptions behind these results, read the explanation below. You can also explore Mass Percent and Molarity.

03 Following one liter through the conversion

At density ρ g/mL, one liter of solution weighs 1,000ρ grams. Multiplying by the mass fraction gives the solute mass in that liter. Dividing by molar mass converts those grams into moles, which gives molarity directly.

The factor of ten in the compact equation combines 1,000 mL per liter with division by 100 for percentage. Enter 10 for ten percent, rather than 0.10. That simple distinction prevents a hundredfold input error.

04 Density must describe the solution

Use solution density at the concentration and temperature of interest. The density of the pure solvent or solid solute is generally not interchangeable with solution density. A dilute-water approximation may be inadequate for concentrated solutions.

This tool is specifically for mass/mass percentage. A mass/volume percentage already supplies grams per 100 mL and uses a different conversion. Solubility, chemical speciation, hydration state, and reagent purity still need to be handled before interpreting the result.