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- Finds the molarity (mol/L) of a solution from mass, molar mass and volume.
- Finds the mass of solute needed for a target concentration.
- Finds the volume of solution you can make.
- Solves dilutions with M₁V₁ = M₂V₂.
How to use the molarity calculator
Choose what to find
Molarity, mass, volume or a dilution.
Enter the molar mass
In g/mol, for example 58.44 for NaCl.
Enter the other known values
Mass in grams, volume in mL or molarity in mol/L.
Read the result
With the moles of solute and each step.
What is molarity?
Molarity is the number of moles of solute per liter of solution. It is the most common way to express concentration in chemistry. To make a solution, dissolve the solute and then add solvent until you reach the final volume.
Molarity formulas
Moles = mass ÷ molar mass
Molarity (M) = moles ÷ liters of solution
Dilution: M₁ × V₁ = M₂ × V₂
Example 1: salt solution
5.844 g of NaCl (58.44 g/mol) in 500 mL.
- Moles 0.1 mol
- Molarity 0.2 M
Example 2: making 1 L of 1 M NaCl
How much salt is needed?
- Mass of NaCl 58.44 g
Example 3: dilution
Make 100 mL of 0.5 M from a 2 M stock.
- Stock needed 25 mL
- Solvent to add 75 mL
Where molarity is used
Chemistry class
Solve concentration and stoichiometry problems.
Lab work
Prepare buffers and standard solutions.
Biology
Make media and reagents at exact concentrations.
Titrations
Work out unknown concentrations.
Convert between mass and volume with the density calculator, or handle very small numbers with the scientific notation calculator.
Molarity calculator FAQ
What is the formula for molarity?
Molarity = moles of solute ÷ liters of solution.
How do you calculate moles from grams?
Divide the mass by the molar mass. 5.844 g ÷ 58.44 g/mol = 0.1 mol.
How much NaCl is needed for 1 L of 1 M solution?
58.44 g.
What does M₁V₁ = M₂V₂ mean?
The moles of solute stay the same when you dilute, so concentration times volume is equal before and after.
What is the difference between molarity and molality?
Molarity is moles per liter of solution; molality is moles per kilogram of solvent.
Where do I find the molar mass?
Add up the atomic masses of all atoms in the formula from the periodic table.