Mass Concentration to Molar Concentration Conversion
Convert between mass per volume and moles per volume using the solute’s molar mass.
01 Set up your calculation
- Choose which concentration you want to find.
- Enter the molar mass of the chemical form actually present.
- Enter the known concentration and select its unit.
02 The relationship
For the assumptions behind these results, read the explanation below. You can also explore PPM to Molarity and Molarity.
Follow the numbers
A 5.844 g/L sodium chloride solution with molar mass 58.44 g/mol has concentration 0.100 mol/L.
03 The numerator changes, the volume does not
A gram describes mass, while a mole describes amount of substance. Dividing the grams-per-liter value by grams per mole leaves moles per liter. Multiplying reverses the operation.
Use solute concentration, not the density of the entire solution. A liquid density of 1,000 g/L does not mean every dissolved substance has that mass concentration.
04 Choose the correct chemical form
Hydrated salts include water in their formula mass. If a weighed reagent is a hydrate, its molar mass can differ substantially from the anhydrous salt. Purity corrections must also be applied before treating an entered mass as pure solute.
The result describes formula-unit concentration. A salt that dissociates can produce several ionic species, whose individual concentrations follow its stoichiometry and equilibrium behavior.
Questions from the notebook
Is 1 mg/mL equal to 1 g/L?
Yes. Both numerator and denominator change by a factor of 1,000.
Can this convert ppm directly?
Only after the ppm basis is identified. A mass fraction needs solution density before conversion to a mass-per-volume value.
References & reading
- OpenStax, Rice University — Chemistry 2e: Molarity ↗
Defines concentration as solute amount divided by final solution volume.
- OpenStax, Rice University — Chemistry 2e: Formula Mass and the Mole Concept ↗
Develops formula-mass addition and conversions among grams, moles and entities.
- NIST — Guide to SI conversion factors ↗
Supports physical unit conversions. Input values are converted to the formula’s base units before calculation.
Our explanations are written for ChemistryCalc. Read how we build and check our tools. These calculations are educational estimates where the underlying model requires assumptions.