Molarity Calculator
Calculate solution molarity from solute mass or moles and the final solution volume.
01 Set up your calculation
- Choose whether you know the solute mass or its amount in moles.
- For a mass entry, provide the correct molar mass.
- Enter the final volume of the complete solution, not only the starting solvent.
02 The relationship
For the assumptions behind these results, read the explanation below. You can also explore Solution Dilution and PPM to Molarity.
Follow the numbers
5.844 g of NaCl at 58.44 g/mol is 0.1 mol. Making the final solution up to 1 L gives a molarity of 0.1 mol/L.
03 Measure the final solution
Adding solute to a measured amount of solvent does not guarantee that their volumes add exactly. The volume used here is the final solution volume after dissolution, at the relevant temperature.
For a preparation calculation, dissolve the solute and make up to the required final volume using an appropriate method. The numerical result does not replace laboratory instructions for a particular substance.
04 Interpret the species concentration
The amount refers to the formula whose molar mass you supplied. If a compound dissociates, the concentration of a particular ion depends on the stoichiometric number of that ion and on any relevant equilibria.
The calculation assumes the entered solute is present in the final solution. Insolubility, chemical reaction, evaporation, and impurities can all make a real preparation differ from a simple mass-over-volume calculation.
Questions from the notebook
Does 1 M mean one mole?
It means one mole per liter. A 0.1 L portion of a 1 M solution contains 0.1 mol.
Why does changing temperature matter?
A solution’s volume can change with temperature, so its molarity can change even if the amount of solute stays fixed.
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.