Work Breakdown Structure (WBS)
A work breakdown structure (WBS) is a hierarchical decomposition of the total scope of work to be carried out by the project team to accomplish the project objectives and create the required deliverables.
Explanation
The WBS is one of the most fundamental project management tools. It organizes the full scope of the project into a tree structure, with the project itself at the top, major deliverables or phases at the next level, and progressively smaller components at each descending level. The lowest level elements are called work packages.
The WBS is deliverable-oriented, not activity-oriented. Each element represents a product, service, or result rather than an action. This distinction is important because activities are derived from work packages during the Define Activities process in Schedule Management. The WBS provides a structured vision of what is to be delivered.
A well-constructed WBS follows the 100% rule: each level must represent 100% of the work in the parent element, and no work should be counted twice. The WBS, together with the project scope statement and WBS dictionary, forms the scope baseline. It serves as a key input to many processes across knowledge areas, including cost estimating, resource planning, risk identification, and procurement planning.
Key Points
- •Hierarchical decomposition of total project scope
- •Deliverable-oriented, not activity-oriented
- •Follows the 100% rule at every level
- •Part of the scope baseline along with the scope statement and WBS dictionary
Exam Tip
The 100% rule is a favorite PMI exam topic. Every level of the WBS must account for 100% of the work in the level above it. No work is omitted and no work is duplicated.
Frequently Asked Questions
Related Topics
Create WBS
Create WBS is the process of subdividing project deliverables and project work into smaller, more manageable components.
WBS Dictionary
The WBS dictionary is a document that provides detailed deliverable, activity, and scheduling information about each component in the work breakdown structure.
Work Package
A work package is the lowest level of the work breakdown structure, representing a deliverable or project work component that can be estimated, scheduled, monitored, and controlled.
Control Account
A control account is a management control point where scope, budget, actual cost, and schedule are integrated and compared to earned value for performance measurement.
Decomposition
Decomposition is a technique used to divide and subdivide the project scope and deliverables into smaller, more manageable parts until the work is defined at the work package level.
Most-studied PMP concepts
High-yield topics our learners drill most before exam day.
Burndown Chart
A Burndown Chart is a graphical representation of work remaining versus time in a Sprint or release, showing whether the team is on track to complete the planned work.
Resource Leveling
Resource leveling is a resource optimization technique in which adjustments are made to the project schedule to keep resource usage at or below a defined limit, often resulting in a longer project duration.
Risk Register
The risk register is a project document that records the details of individual project risks, including their identification, analysis results, response plans, and current status.
Stakeholder Mapping
Stakeholder mapping is the visual representation of stakeholder relationships, influence, interest, or other attributes using grids, matrices, or diagrams to support analysis and engagement planning.
Relative Estimation
Relative Estimation is an agile technique where work items are sized in comparison to each other rather than in absolute units like hours or days, providing faster and more accurate estimates.
Cost Performance Index (CPI)
Cost Performance Index (CPI) is an EVM efficiency metric that measures cost performance as the ratio of earned value to actual cost: CPI = EV / AC.
Schedule Performance Index (SPI)
Schedule Performance Index (SPI) is an EVM efficiency metric that measures schedule performance as the ratio of earned value to planned value: SPI = EV / PV.
Earned Value Management (EVM)
Earned Value Management (EVM) is a methodology that integrates scope, schedule, and cost data to assess project performance and progress objectively.
Power/Influence Grid
The power/influence grid is a stakeholder classification model that groups stakeholders based on their level of authority (power) and their active involvement or ability to affect the project (influence).
Part of
Scope Management
Test your knowledge
Practice scenario-based questions on this topic with detailed explanations.