Where:

C = common concentration (g / L)

m_{1} = mass of solute (g)

V = volume of solution (L)

Example:

What is the common concentration in g / l of a 3L solution with 60 g of NaCl?

Common concentration is different from density, although the formula is similar. See the difference:

The density is always the solution, so:

At the common concentration, only m_{solute}, ie m_{1}.