Determine the amount of dissociated (ionized) acid or base in the solution. Often, this information is given in the problem. If you are in a more advanced class, you must calculate the amount hydrogen or hydroxide ions using experimental research or formula chains.
Divide the amount of dissociated acid or base, which is given in units of moles per liter, by the initial concentration of the acid or base, which is also in moles per liter. Most often, you know the initial concentration from the label on the bottle from which you poured the chemical, or from the problem.
Multiply this figure by 100. This is the percentage that represents the degree of ionization.