What Are Function Points in Software Engineering?

Published: 27 February 2023

Function points are one of the most commonly used measures of software size and complexity. In this article, we’ll take a look at what function points are, how they’re calculated, and some of the benefits and drawbacks of using them. Whether you’re just getting started in software engineering or you’ve been doing it for years, understanding them can be a valuable tool in your development arsenal.

Defining function points and how they are used in software engineering

A function point is a unit of measurement used to quantify the amount of business functionality being delivered by a software application. Function points allow software engineers to better measure the size of a project, identify areas in need of optimization, and analyze development performance benchmarks over time. Due to its accuracy and flexibility, function point analysis has become a standardized tool for studying application complexity. Through the evaluation of data elements, transaction types, external inputs, outputs and inquiries within an application, calculations are performed to translate user requirements into uniform standards which can then be measured against industry baselines. This generalised method for measuring virtually any type of IT system ensures engineers have the data needed to correctly assess the scope of a project for cost estimation and process improvement purposes.

The benefits of using function points to measure software size

Function point analysis is an effective method for measuring software size. By focusing on the features and functions that a user can access and use, this metric can accurately determine the complexity of an application. They are especially useful when comparing projects of different sizes; they provide a consistent method for assessing and measuring project scope, instead of asking developers to estimate the number of lines of code each project requires. Additionally, because they take into account differences between programming languages, function points are particularly beneficial during development or design changes. Not only do they allow insightful comparisons between systems of differing sizes and structures, but also provide a wide range of other benefits such as identifying development bottlenecks or highlighting discrepancies in customer specifications. Ultimately, they offer an effective way to measure the size of software projects at any stage in its lifecycle — from planning to implementation.

Comparing and contrasting with other measures of software size, such as lines of code

Function points serve as an effective measure for determining the relative size of a software system as it allows for quantifying the efforts associated with developing and maintaining the system. Initially limited to only certain languages, such as COBOL, function points have since become more dynamic and flexible in accommodating other widely used languages like Java.

In comparison to lines of code (LOC) metrics, function points are capable of providing a more holistic view in terms of evaluating the complexity of software development that takes into account key factors such as data elements, data files, user inputs and outputs. Moreover, since function points take into consideration the type of each element instead of merely counting them, it helps to assign a proper “size” metric even if the code varies drastically in length.

Thus, while both approaches are essential in measuring software size, function point analysis offers more varied and specific aspects which makes it more advantageous compared to LOC metrics.

Some examples of how they can be used to estimate the cost and effort required for a software project

Function points can be a valuable tool for determining the expense, time, and effort needed to successfully complete a software project. The cost calculation of such projects can vary depending on their scope and complexity, making function points an advantageous tool for estimating the relative cost. For example, the Inputs Model is an effective method for calculating time and effort which uses values associated with the number of user inputs to determine the project’s cost. The Outputs Model also takes into account factors such as output record types, inquiries, interface files, external programs and reports to better determine total project cost. These models highlight how function points effectively identify even subtle elements of a software project in order to make accurate estimations.

Some of the drawbacks of using Function Points

Function points are widely used as a measure of software size, but their use also comes with potential drawbacks. The difficulty of assigning accurate values to the complexity factors makes function point analysis unreliable. Further, installing and running a software sizing tool can be expensive, making it impractical for smaller teams or projects.

Moreover, since different types of user experiences require different weights when assessing the complexity of an application, manually determining the weights is both time-consuming and subjective.

Finally, It should also be noted that parameters like bugs or maintenance support have no representation, which further reduces their effectiveness as an absolute measure of software size.

In conclusion, function points have emerged as a key tool for measuring the size of a software product. Not only do they provide an objective metric for sizing software, but they are also easy to count and allow for accurate comparison between different programs. Furthermore, the use of function points facilitates faster and more accurate estimates of cost and effort associated with a software project. However, it’s important to remember that the use of function points isn’t without its drawbacks; potential miscalculations may impact on both finance and timeline estimates.

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