The Tocris molarity calculator is a useful tool which allows you to calculate the:

- mass of a compound required to prepare a solution of known volume and concentration
- volume of solution required to dissolve a compound of known mass to a desired concentration
- concentration of a solution resulting from a known mass of compound in a specific volume

### The molarity calculator equation

The Tocris molarity calculator is based on the following equation:

**Mass (g) = Concentration (mol/L) x Volume (L) x Molecular Weight (g/mol)**

### An example of a molarity calculation using the Tocris molarity calculator

What is the mass of compound required to make a 10 mM stock solution in 10 ml of water given that the molecular weight of the compound is 197.13 g/mol?

- Enter 197.13 into the Molecular Weight (MW) box
- Enter 10 into the Concentration box and select the correct unit (millimolar)
- Enter 10 into the Volume box and select the correct unit (milliliter)
- Press calculate
- The answer of 19.713 mg appears in the Mass box