What is a work breakdown structure?
A WBS divides the total scope of a project into smaller, manageable pieces, so each can be estimated, assigned and tracked.
The core rules
- The 100% rule. The children of an item must add up to everything in that item, and nothing outside it.
- Describe outcomes. Use nouns for deliverables ("Wireframes") at upper levels; verbs for work packages ("Draft wireframes") at the bottom.
- Stop when a piece is estimable. A task someone can finish in about 1 to 10 working days and own is small enough.
- Do not show sequence. A WBS says what, not when. Order comes from dependencies.
How to build one
- Write the project's end result at the top.
- List the major phases or deliverables.
- Split each until you reach work packages.
- Number them hierarchically (1, 1.1, 1.2).
- Add owners and durations.
From WBS to schedule
Add predecessors and you get a schedule: see dependency types and the critical path method. In GenuinePlan the WBS is the table, and the Gantt chart is drawn from it. See WBS software.
Frequently asked questions
WBS vs task list: what is the difference?
A task list is flat. A WBS is hierarchical and covers the whole scope, so you can check nothing is missing.
How many levels should a WBS have?
As many as it takes to reach estimable work packages. Three to four levels is common for small projects.
Related
Work breakdown structure
Break the project down into phases, deliverables and tasks, number them automatically, and roll their dates and progress up to the top.
Read more →Critical path method
The critical path is the longest chain of dependent tasks. It sets the shortest possible project duration.
Read more →Dependency types
A dependency says how one task's timing relates to another's. There are four types, and lag or lead fine-tunes them.
Read more →Plan your first project in a few minutes.
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