Molarity Calculator
Solve concentration, moles, and volume with M = n/V.
Use independent solution calculators for mass, volume, molarity, and stock dilution. Formula weight can be typed directly or calculated from a chemical formula.
How to Use the Molarity Calculator
1
Pick what you are solving for. Choose mass from volume and concentration, volume from mass and concentration, molarity from mass and volume, or a stock dilution.
2
Enter values and units. Type the known quantities and select their units. The formula weight can be typed directly or calculated from a chemical formula.
3
Read the preparation steps. The result gives the answer in your chosen unit along with the substituted equation you can copy into a lab notebook.
What is the Molarity Calculator?
The molarity calculator solves the concentration equation M = n/V in any direction: molarity from moles and volume, moles from molarity and volume, or the volume needed to reach a target concentration. It also supports mass-based input using molar mass, with automatic conversion between mL and L.
Molarity is the default concentration unit in chemistry labs, so this calculation appears in solution preparation, titration, dilution, and reaction stoichiometry. The calculator shows each conversion step so the workflow transfers directly to hand calculations.
Common Uses
- Find the molarity of a prepared solution
- Calculate moles of solute in a given volume
- Determine the volume needed for a target concentration
- Convert grams of solute into molar concentration
How to Solve It by Hand
Manual calculation is still important: identify the known variables, convert units before substitution, apply the equation, and check whether the result is chemically reasonable. The most common mistakes are inconsistent units, constants rounded too early, and skipping the interpretation step.
Practice Prompt
Try changing the default values and ask the lower-right chemistry chat why the result increased or decreased. That turns the calculator from a number machine into a study loop.
Molarity is moles of solute divided by litres of solution: M = n/V. To get moles from a mass, divide the mass in grams by the molar mass in g/mol first.
Use m = C × V × FW. For 250 mL of 0.10 M NaCl: 0.10 mol/L × 0.250 L × 58.44 g/mol = 1.46 g. The mass mode does this conversion with any combination of concentration, volume, and mass units.
Molarity is moles per litre of solution and changes with temperature because volume expands. Molality is moles per kilogram of solvent and does not change with temperature, which is why colligative property calculations use molality.
Add solvent up to the mark. Molarity is defined per litre of finished solution, not per litre of solvent, so dissolve the solid in a smaller volume first and then make up to the final volume in a volumetric flask.
Yes. Type a chemical formula such as CuSO4.5H2O and use the formula weight button; the parsed molar mass is filled into the calculation automatically.