Cost accountants want to support decision making. To do so, they should not only calculate current costs and income, but they should also be able to tell managers how costs might change depending on managers' decisions. "How would costs change if we produced more or less products? How would they change if we produce more or less variants of products? How would they change if we increase the quality of our products?" Cost functions help to answer these questions and in this module, we make you familiar with them. First, we show you some typical cost functions and, second, we introduce a variety of methods that cost accountants can use to determine cost functions. Finally, we show you how accountants can document cost forecasts.

When companies consider offering a new product, they might want to know how many units they need to sell in order to avoid losses or to achieve a targeted profit. Cost-volume profit analysis is a simple tool that helps answer these questions. It illustrates how costs, revenues, and profits depend on sold quantities.

In the beginning of this course, you learned that companies use Cost Accounting to support managers' decision-making. In this module, we outline some business decisions and discuss how cost information can support them best. For example, we discuss pricing decisions and product-mix decisions under capacity constraints.