What is a Work Breakdown Structure (WBS)?

A Work Breakdown Structure (WBS) is a hierarchical decomposition of the project scope into smaller, more manageable components. It provides a visual representation of the project’s deliverables, tasks, and subtasks, enabling effective project planning, resource allocation, and progress tracking.

Understanding the Work Breakdown Structure (WBS)

A Work Breakdown Structure (WBS) is a foundational project management tool used to organize and define the scope of work required to complete a project. By breaking down the project into smaller, more manageable components, the WBS provides a structured framework for project planning, execution, and control.

What is a Work Breakdown Structure (WBS)?

A Work Breakdown Structure (WBS) is a hierarchical decomposition of the project scope into smaller, more manageable work packages. It organizes project deliverables, tasks, and subtasks in a logical and structured manner, allowing project teams to identify and understand the work required to achieve project objectives.

Key Components of a Work Breakdown Structure (WBS)

An effective WBS typically includes the following components:


The WBS is organized hierarchically, with higher-level components representing major deliverables or phases of the project, and lower-level components breaking down these deliverables into smaller, more detailed tasks and subtasks.

Work Packages

Each component of the WBS represents a work package, which is a unit of work that can be planned, executed, and controlled independently. Work packages should be defined at a level of detail that allows for accurate estimation, resource allocation, and progress tracking.

Numbering System

The WBS uses a numbering system to uniquely identify each component, making it easier to reference and manage. The numbering scheme typically follows a hierarchical structure, with each level of the WBS assigned a different set of numbers or codes.

Scope Control Points

The WBS includes scope control points, such as milestones or deliverables, that mark significant stages of the project and enable progress monitoring and control.


The WBS dictionary provides detailed descriptions of each component, including its purpose, objectives, dependencies, resources required, and estimated duration.

Benefits of Using a Work Breakdown Structure (WBS)

Utilizing a WBS offers several benefits to project teams, including:


Provides a clear and structured framework for understanding project scope and requirements.

Scope Management

WBS facilitates effective scope management by defining project deliverables and breaking them down into manageable work packages.

Resource Allocation

WBS enables accurate resource allocation and assignment by identifying the specific tasks and activities required to complete the project.

Progress Tracking

WBS supports progress tracking and performance measurement by establishing scope control points and defining the work packages necessary to achieve them.

Risk Identification

WBS helps identify potential risks and dependencies early in the project lifecycle by breaking down the project into smaller, more manageable components.

Types of Work Breakdown Structure:

There are two main types of WBS: Deliverable-Based and Phase-Based.

Deliverable-Based Work Breakdown Structure

The Deliverable-Based approach clearly establishes the relationship between project deliverables (such as products, services, or results) and the work to be executed. It helps identify the unique deliverables required to create each summary deliverable. This approach is commonly preferred due to its effectiveness in managing project scope.

Phase-Based Work Breakdown Structure

The Phase-Based approach organizes the work into typical project phases. Each phase consists of unique deliverables to be executed. While this approach is useful, it requires additional effort to divide work associated with multiple elements into the work specific to each level 1 element.

How to create a Work Breakdown Structure

To create an effective WBS, project managers should follow these steps:

  1. Gather Critical Documents:
    Collect important project documents, including the Project Charter, Scope Statement, and Project Management Plan (PMP) subsidiary plans. These documents contain valuable information about project deliverables.
  2. Identify Key Team Members:
    Analyze the collected documents to identify the project deliverables and involve the appropriate team members in the process.
  3. Define Level 1 Elements:
    Define the Level 1 Elements, which are summary deliverable descriptions that capture 100% of the project scope. This ensures that the WBS covers all the necessary work.
  4. Decompose (Breakdown) Elements:
    Break down the Level 1 deliverables into unique lower-level deliverables. Continue this process until each element is managed by a single individual or organization. Avoid over-decomposition, as it can lead to unnecessary effort in managing the project.
  5. Create WBS Dictionary:
    Develop a WBS Dictionary, which provides a narrative description of the work covered in each element. It includes information such as boundaries, milestones, risks, owners, and costs. The lowest-level elements in the WBS are called Work Packages, which contain detailed information about the deliverables.

Best Practices for Creating a Work Breakdown Structure (WBS)

To maximize the effectiveness of a WBS, consider the following best practices:

Involve Key Stakeholders: Collaborate with project stakeholders to ensure that the WBS accurately reflects project objectives, requirements, and constraints.

Keep it Flexible: Design the WBS to be flexible and adaptable to changes in project scope, schedule, or resources.

Use Consistent Terminology: Maintain consistency in terminology and naming conventions to ensure clarity and avoid confusion.

Review and Validate: Regularly review and validate the WBS with project team members and stakeholders to ensure accuracy and alignment with project goals.

Update as Needed: Update the WBS as needed throughout the project lifecycle to reflect changes in project scope, requirements, or priorities.

How to Use a Work Breakdown Structure

A WBS serves multiple purposes throughout the project lifecycle. It acts as a planning tool to help define, organize, and manage project scope and deliverables. It also serves as a primary source for schedule and cost estimation activities. Moreover, the WBS facilitates monitoring and controlling project progress.

Work Packages:
Work Packages are the lowest levels of the WBS and provide detailed information about the deliverables, including owners, milestones, durations, resources, and risks. This information is described in the WBS Dictionary.

Planning Packages:
In cases where project details are not fully known, Planning Packages are created. These packages capture the scope that is yet to be defined and evolve into Work Packages as more details become available. This planning process is known as Rolling Wave Planning and is a form of Progressive Elaboration.

Control Accounts:
The WBS also serves as a monitoring and controlling tool through the use of Control Accounts. These accounts are specific WBS elements where project performance is monitored and reported. Control Accounts can be at any level in the WBS, depending on the project’s needs.


A Work Breakdown Structure (WBS) is a fundamental project management tool that provides a structured framework for organizing and defining project scope. By breaking down the project into smaller, more manageable components, the WBS enables effective project planning, execution, and control, ultimately contributing to project success.

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