Work Breakdown Structure (WBS), the Basic Building Block for a Project Plan

Get the work breakdown structure right and you increase the chances of project success. Get this wrong and you may be looking at a poor project performance or worse, the classified ads. One of the biggest mistakes that project managers make when developing a project plan is to not sit down with the team doing the work and guessing for them. Too many times, managers at the early stage of the project sit down with only one person and ask that person for all the estimates on the time required, only to face serious consequences later in finding out how off the estimates were.

Table of contents

What is WBS?

Back to top

The PMI gives the WBS meaning to be a deliverable-oriented hierarchical decomposition of the work executed by the project team to accomplish the objectives and create the required deliverables. The definition tells us who is responsible, what it is, and for what purpose. So, if you have a large project, the project team creates the WBS to help break the project down into smaller, more manageable and measurable deliverables that describe planned outcomes rather than planned actions.

WBS levels

Back to top

As a hierarchy, a WBS contain at least three levels, but can contain more depending on the complexity and size of a project. The WBS levels are:

  • First level: Project title of final deliverable
  • Second level: Major deliverables or controls account
  • Third level: Work packages that are deliverable to the customer
  • Fourth level: Activities assigned to team members to complete work packages

All levels of a WBS should contain verifiable pieces of work. Project stakeholders can verify activities through completed schedules or milestones. Some branches of a WBS can appear more subdivided because of project complexity. But most branches should have about three to four levels as a rule.

Read also: WBS Types (Work Breakdown Structure)

WBS formats

Back to top

The hierarchy of a WBS can take different formats. Here are some examples.

Outline format

The WBS outline is the simplest format for breaking down a large project or major deliverable. But it can also contain minimum details and exclude information such as assignment, duration, or budget.

WBS outline format

Table format

The WBS tabular format provides a more visual depiction of the hierarchy. It can also contain details such as numbers and additional description.

WBS table format

Tree format

The tree format is a common WBS project management chart that provides a more visual information among the other formats. The hierarchy structure is similar to an organization chart and allows easy editing for additional information.

WBS tree format

A WBS comes with a dictionary. It is a document with a similar format to the hierarchical structure and includes a brief description of each deliverable and work package. It helps team members understand better the scope of the tasks they have to complete to deliver the work.

Importance of a WBS

Back to top

Breaking down a large, complex project using a WBS is an organized way of planning, executing, monitoring, and delivering the project successfully. With a breakdown of the project into deliverables and work packages, project managers are able to perform the following tasks more accurately:

  • Estimate the project cost
  • Establish task dependencies
  • Develop a project schedule
  • Determine the project timeline
  • Write a statement of work
  • Plan project resources
  • Assign responsibilities and roles
  • Track the progress
  • Identify project risks

Simple Way to Create a WBS

Back to top

Here is a simple yet effective way to create a WBS and get it right.

Identify: Goals to Deliverables

The first step is to define the project goals and objectives. Determine if the project will span across phases. Make a list of all deliverables from the proposal, contract, or scope statement. The following is a work breakdown structure example of a software development project.

WBS example

Break it down

From the list of deliverables, create sub-deliverables. These work packages define the amount of work that the project manager can track to monitor project progress. These are hierarchically above the activities or tasks needed to complete them.


Sit with experts or knowledgeable staff from all areas of your project when creating the WBS. For a software development project, the project manager should sit with at least four people: the UI designer, developer, tester and a software development manager who overseas the team. This is not too much. A 30-minute meeting with each person now will save the company in the long run.

Read also: Work Breakdown Structure for IT Projects (WBS)


Ask questions such as “what next?, how long?, or who with?” in order to nail down as much detail as possible. This is not necessarily a part of the WBS but ensures that you have all the relevant information overlooked when working on the project scheduling.

WBS best practices

Back to top

Project teams can make sure that their WBS are comprehensive and realistic with the help of some best practices to guide them.

100% rule

The WBS should represent 100 percent of the work necessary to complete the project. So, every major and minor deliverable constitute a percentage that when summed up results to 100 percent. This also means that you should avoid duplication so that every item in the WBS is mutually exclusive and helps you plan for resources accurately.

Outcomes, not actions

Focus on outcomes and deliverables, not actions. Outcomes are the desired ends of the project such as a product, service, or result.

8/80 rule

Follow the 8/80 rule to ensures that no task is less than 8 hours or more than 80 hours in the WBS. If a task is greater than 80 hours then you need to decompose it further into lower-level work packages.

Create your WBS with the right PM software

Back to top

A WBS is not the project plan or a Gantt chart, yet it is an important element and input to the project plan and leads to cost and time estimates. The accuracy of these estimates depend on the WBS, which is why it is extremely important to get it right. With the help of project management software, you can easily choose a work breakdown structure template and use automation to graph the deliverables, milestones, and tasks into timelines and Gantt charts.

WBS template Smartsheet

Quratulain Habib, PMP

Quratulain Habib (Q Habib) is a professionally trained (PMI) project manager with experience of detailed planning, HR management, reporting and closing projects to deliver results aligned to project & organisational objectives. LinkedIn Profile