Calculate molarity, solute mass, or solution volume with real unit conversions, or solve any term of the C1V1 = C2V2 dilution equation.

Use final solution volume, not solvent volume. Dilution assumes conservation of the same solute with no reaction or loss. These calculations do not establish solubility or preparation safety.

Molarity Formula

The molarity calculator uses the relationship between moles of solute, liters of solution, and molarity.

M = n / V
n = M × V
V = n / M
  • M = molarity, in moles per liter, usually written as M or mol/L
  • n = moles of solute, in mol
  • V = volume of solution, in liters

To calculate molarity, select the amount-in-moles basis and enter solute amount and final solution volume, or select the mass basis and also supply molar mass. The calculator divides moles by liters.

To calculate solute amount, select Solute mass or amount and the amount-in-moles basis, then enter molarity and final volume. The mass basis additionally requires molar mass to return solute mass.

To calculate volume, enter moles and molarity. The calculator divides moles by molarity.

If you use mmol, μmol, mL, mM, or μM, the values are converted to base units first. Moles are converted to mol, volume is converted to L, and molarity is converted to M before the formula is applied.

Molarity Units and Conversions

Use these conversions to check that your inputs use the correct scale.

Quantity Unit Base-unit conversion
Amount of solute 1 mol 1 mol
Amount of solute 1 mmol 0.001 mol
Amount of solute 1 μmol 0.000001 mol
Volume 1 L 1 L
Volume 1 mL 0.001 L

Molarity unit Equivalent in M Equivalent description
1 M 1 M 1 mole per liter
1 mM 0.001 M 1 millimole per liter
1 μM 0.000001 M 1 micromole per liter

Example Problems

Example 1: Calculate molarity

You dissolve 0.50 mol of solute in enough solution to make 2.00 L. Find the molarity.

M = n / V = 0.50 / 2.00 = 0.25 M

The molarity is 0.25 M.

Example 2: Calculate moles

You have 250 mL of a 0.200 M solution. Find the moles of solute.

First convert 250 mL to liters:

250 mL = 0.250 L

Then multiply molarity by volume:

n = M × V = 0.200 × 0.250 = 0.0500 mol

The amount of solute is 0.0500 mol, or 50.0 mmol.

FAQ

What does molarity mean?

Molarity is the number of moles of solute per liter of solution. A 1 M solution contains 1 mole of solute in each liter of solution.

Is volume the amount of solvent or the total solution?

Use the total final volume of the solution. For example, if you dissolve a solid in water and then dilute the mixture to 500 mL, the volume is 500 mL. It is not just the amount of water you started with.

Which inputs does each calculation require?

Select the value to find. For c = n/V, the other two quantities are required. Using solute mass instead of moles also requires the matching molar mass. Each dilution solve requires the other three C1V1 = C2V2 quantities. Inputs that cannot identify a unique answer are rejected.