A function point is a unit of measurement to express the amount of business functionality an information system (as a product) provides to a user. Function points measure software size. The cost (in dollars or hours) of a single unit is calculated from past projects. As of 2013, there are several recognized standards and/or public specifications for sizing software based on Function Point. 1. ISO Standards. 1  COSMIC: ISO/IEC 19761:2011 Software engineering.