The Putnam Savings Growth Calculator is a useful tool that helps investors estimate how much money they will need for a comfortable retirement. Since this is an issue many people avoid, we felt that the calculator needed to be engaging and easy to use for those who are not financially adept. The calculator has two sides: one that allows you to determine how much you will have for retirement, based on a monthly investment; the other based on a percentage of your annual salary. The interactive design makes the calculator enjoyable and encourages people to experiment with a number of financial scenarios.