A Guide to Functional Requirements (with Examples)

Learn how to define requirements and keep all stakeholders aligned.

Getting the requirements right is the key to the success of any project. Failure to accurately define and document them inevitably results in miscommunication between stakeholders, constant revisions, and unnecessary delays. Studies show that unclear or poorly documented requirements can increase the project timeline and budget by up to 60%.

With the growing popularity of the Agile approach to documentation, some teams have started to neglect documenting requirements – after all, it's "working software over comprehensive documentation", right?

Alas, it's a common misconception, and foregoing proper internal documentation can be particularly damaging when it comes to requirements. In this article, we'll dive deeper into what functional requirements are and why it's vital to document them.

What are functional requirements?

Functional requirements are product features that developers must implement to enable the users to achieve their goals. They define the basic system behavior under specific conditions.

Business requirements, user requirements, product requirements, functional requirements, non-functional requirements

Functional requirements should not be confused with other types of requirements in product management:

Functional requirements may be captured as part of a product requirements document (PRD) or in the form of a separate functional requirements document (FRD). Here's an example of what such a document may look like in Nuclino, a unified workspace for all your team's knowledge, docs, and projects – create an account and start documenting your requirements in one central place:

Functional requirements document in Nuclino

Why functional requirements need to be documented

Documenting and aligning on functional requirements has numerous benefits:

If your company specializes in developing custom software solutions, such as third-party API integrations or complex data management systems, the meticulous documentation of functional requirements becomes even more critical. Clear documentation ensures that the tailored solutions you deliver align precisely with your clients' unique needs.

Functional requirements examples

Functional requirements need to be clear, simple, and unambiguous. Here are some examples of well-written functional requirements:

Contrary to a popular misconception, functional requirements are not analogous to user stories, but stories can be a useful tool for deriving requirements with the user in mind. For example: