Function Point Analysis (FPA) is a method to measure the functional size of an information system. FPA measures the functional size by looking at the (functional) transactions and (logical) data files that are relevant to the user in the business.
The unit of measurement is "function points"; the functional size of an information system is expressed by a number of function points.
Function points are a good measure of the functional size of an information system; the unit of measurement "function points" can be utilized in various ways.
FPA is often used to budget a system development project. The
development costs for an information system are related to its size: the
bigger the system, the more expensive the development will be.
Based on experiences in earlier projects an organization knows, how many hours (on average) one needs to realize one function point: the productivity rate.
Size (number of function points) x productivity rate (hours per function point) is a basis for the project budgeting process.
FPA can be applied for development, as well as for enhancement projects.
FPA is a fast method, which does not require knowledge of computers. Assuming suitable documentation, it does not take much time to perform an FPA. It is estimated that for a system which needs one thousand development hours, an FPA can be performed in about one hour.