WBS · Work Breakdown Structure
Work Breakdown Structure
What is a WBS?
- Hierarchically breaking a project down into deliverables
- The 100% rule: your scope baseline
- Keep work packages to two weeks or less
Once you draw a WBS, the language in your meetings changes. A status report of “design is in progress” becomes “3 of 5 course materials finalized, 2 awaiting review.” The test for “done” shifts from personal judgment to a tangible deliverable, and that is what this tool really changes. Team members can see exactly what remains, and the PM stops estimating progress by feel and instead calculates it from the number of finalized deliverables.
There are three main ways to decompose work: by deliverable, by phase (planning, design, execution, closure), or by organization (department). For smaller projects, it is safer to use deliverables alone all the way down. Three to five levels are enough for most projects; beyond six, the effort of managing the structure outweighs the information it gives you. Give every work package a unique code such as 1.2.3, and write its deliverable definition, acceptance criteria, and predecessors in three lines in the WBS dictionary. That ends arguments over whether something is actually done. Keep in mind that the WBS covers only the “what”; the “when” and “who” are handled by the schedule and the RACI chart.
The most common failure in the field is copying the org chart straight into the WBS. If branch 1 goes to Planning and branch 2 to Operations, work that straddles the boundary between the two departments disappears entirely, and comes back at the last minute as “That’s not our job.” Verb-style names are the same trap. “Recruit instructors” invites arguments about where it ends, whereas “Final profiles for 12 instructors” is done once you count them.
The last category is management work. Weekly meetings, quality reviews, executive reporting, and audit support leave no tangible deliverable, so they often drop out of the WBS, yet they consume a good share of actual effort. It’s better to give project management its own branch. Also, when scope changes, many teams reach for the Gantt chart first, but that is backward. A schedule change made without updating the WBS only pushes dates out while leaving the missing work in place, so the same delay recurs a month later.
John KimAuthor of B2B Marketing Design and CEO of Nanum Consulting
Eunpyo HongExpert in company analysis, startups, and venture fundraisingIt was formalized in the 1960s in the management of large U.S. Department of Defense and NASA projects, and became the standard scope management tool in PMI’s PMBOK Guide.
Consider a hypothetical case. Company A, a cosmetics OEM manufacturer with 540 employees, decided to build a training system for frontline leaders within four months, in time for its second plant to open. Two months after kickoff, the progress figure in the weekly report was still stuck at 60%. The schedule had only nineteen vague lines, such as “develop course materials.”
- When Kim, who leads training planning, suggested, “Let’s list everything tangible this project produces,” the list came to 37 deliverables, nearly double the 19 in the schedule.
- The 18 missing items included the instructor qualification review criteria, textbook printing and delivery, and the assessment question review confirmation. The 9-business-day print lead time hadn’t been counted at all.
- The single three-week line item “develop course materials” was split into 15 work packages: a draft, a reviewed version, and a final version for each of 5 modules. None was allowed to run longer than 6 days.
- When Park, an operations manager, asked, “Where are the 16 weekly meetings and the 3 executive reports?”, the team set up management work as a separate branch 0. Added up, it came to 0.4 FTE.
- The opening date held to the original schedule. With no more rush printing or extra outsourcing, outsourcing costs fell from KRW 42 million (≈ US$31,400) to KRW 33 million (≈ US$24,700), and weekly reporting time dropped from 90 to 35 minutes.