How to calculate the molarity of a solution where you are given the weight percent!

Molarity of solutions where the concentration of the solution is given in wt %:

[(% x d) / MW] x 10 = Molarity;

Where:
% = Weight % of the acid;
d = Density of acid (specific gravity can be used if a density value is not available);
MW = Molecular weight of the acid.
Also, Sigma Aldrich has an online calculator which automatically calculates the Molarity and the Normality of the solutions.

Source: http://www.sigmaaldrich.com/united-kingdom/technical-services/uk-technical-services2.html