A method and apparatus for providing a Medicare Part D Pharmacy Benefits Calculator. A user inputs data for prescriptions to be purchased by a prospective insured for a plan period. The prescription data includes a quantity, a days supply, and a number of fills. The data for each prescription the user enters is used to calculate anticipated out-of-pocket costs for the prescriptions for one or more pharmacy benefits plans available to the prospective insured. The cost data is presented to the user in a way that illustrates how out-of-pocket costs will vary over the course of a plan period. The user may view costs for alternative drugs and alternatives sources of drugs. The user may vary and expand the presentation of the cost data to better understand the available plan benefits. The invention helps prospective insureds decide among alternative Medicare Part D pharmacy benefits plans offered by one or more insurance companies.