What is a Work Breakdown Structure (WBS)?

What is a Work Breakdown Structure (WBS) in project management?

Careful planning is the key to improving the project success rate. But how does one plan gargantuan projects such as dam constructions, or building entire cities?

Whenever project managers find themselves in a situation where the work in front of them is so large that they can’t make heads or tails of it, they tend to ask themselves “How can I divide this one project into a lot of tiny projects that aren’t as scary?” 

Well, maybe not in those exact words, but you get the gist.

Because this is such a common problem in the project management world, there is actually a document that serves this exact purpose. 

This document is called the Work Breakdown Structure, or WBS, for short, and it’s so important that not having one — or having a poorly developed one — is directly linked to complete project failure, as some researchers claim.

So, to help you get acquainted with this type of PM document, this guide will go over everything you need to know about the Work Breakdown Structure in great detail — you’ll learn:

  • What a Work Breakdown Structure (WBS) is, 
  • What a WBS is for, 
  • How to develop a WBS, and 
  • Much more. 

So, if you’re interested in this project management topic, put your learning cap on, and let’s get started!

What is a Work Breakdown Structure (WBS)?

Imagine you’ve ordered a large pizza. Your “project” is to eat it whole.

You obviously can’t eat an entire pizza in one bite. You also realize it’s too large to eat by yourself, so you call some friends over, and each of them gets a few slices. 

However, instead of eating all of your slices of pizza at once, you eat them one by one, bite by bite, until there is no more pizza left.

In a way, that is what a WBS is — a graphic representation of a project being divided into smaller, more manageable chunks. And then, those chunks being subdivided into even smaller, bite-sized units.  

A WBS is created during the planning phase of the project lifecycle. 

Along with the Scope Statement and the WBS Dictionary, it is an element of the Scope Baseline, which is itself part of the Project Management Plan.

Now, the WBS is a graphical representation of the scope division that’s most commonly created in the form of a tree diagram. 

However, while not as common, A WBS can also be found in the form of a table, outline, or any other structure that clearly shows the hierarchy of WBS elements. This makes it incredibly easy to create a WBS in any Project Management software, such as Plaky

Example of a WBS in Plaky (project management software)
Example of a WBS in Plaky (project management software)

The example above shows a simple WBS for a pizza-making project in Plaky. It illustrates a four-tier WBS, with each of the levels numbered appropriately to show the level hierarchy.

The first level is occupied by the project deliverable (pizza) and the second by the five main phases of the project (planning, acquisition, preparation, baking, and eating), followed by the activities needed to complete the phases.

This manner of a work division makes any project seem more approachable and manageable. 

What is a WBS Dictionary?

The WBS Dictionary is a necessary companion to the Work Breakdown Structure. Since the WBS is a very simple division of work that doesn’t contain any additional information about the deliverables or activities listed in it, it’s necessary to create a separate document with all the details.

The WBS Dictionary is written by the project manager and it contains all the minutest information about every single item in the Work Breakdown Structure. This includes:

  • Estimated length,
  • Estimated cost,
  • Due date,
  • Acceptance criteria,
  • Dependencies, 
  • Approvers, etc.

Due to its acute attention to detail, the WBS Dictionary is a hefty document that can get hundreds of pages long. 

This is one of the reasons organizations may choose to stop their WBS at the third level (work packages), and exclude smaller activities and tasks. This way they avoid wasting time on writing exhaustive WBS Dictionary entries for comparably insignificant tasks.

Types of Work Breakdown Structures (WBS)

Typically, there are two main types of Work Breakdown Structures:

  1. Deliverable-oriented, and
  2. Phase-oriented. 

Both of these look the same visually, but they present information in different ways. The main difference is the way they divide the work at the second level. 

Let’s take a closer look at them.

Deliverable-oriented WBS

Deliverable-oriented WBS is also sometimes called noun-oriented

It lists all the smaller products of work that, put together, comprise the final product. 

In other words, it names the items by their expected outcomes (deliverables) instead of the actions needed to achieve them.

Deliverable-oriented WBS
Deliverable-oriented WBS

Note that the items on the second level are named after the four main deliverables needed to complete a website (plan, website design, website code, and website content). 

These are then divided into their smaller constituents, also written in the form of nouns (web pages, graphics, blog, etc.).

Phase-oriented WBS

The phase-oriented WBS is also known as verb-oriented

This type of structure prioritizes the phases of the project’s lifecycle and the activities that comprise those phases instead of the outcomes of those activities. 

Phase-oriented WBS
Phase-oriented WBS

In the example above, the second level of the WBS highlights the main phases of the project at hand (initiation, design, code, test, and closing phase) as opposed to the deliverables in the previous example. The rest of the phase-oriented WBS reads more like a to-do list since it is formulated as a set of instructions.

There are no specific rules about using one type of WBS or the other. This entirely depends on the type of project, the organization, and the preferences of the project manager.

What are the levels of a Work Breakdown Structure (WBS)?

To hierarchically decompose (as is the official term) a project into its smaller deliverables, we must first understand the elements of that hierarchy — i.e., the WBS levels. 

While the naming conventions sometimes differ from organization to organization, the most common names for the WBS elements/levels, (also known as WBS building blocks), are as follows:

  • Project deliverable,
  • Deliverables/Phases,
  • Work packages,
  • Activities, and
  • Tasks. 
The levels of a Work Breakdown Structure (WBS)
The levels of a Work Breakdown Structure (WBS)

Let’s see what each WBS element is about, in more detail.

Level 1: Project deliverable

The project deliverable — also known as the product of the project, or the work product — is the final product that the project manager and the project team are trying to create. It stands alone at the top of the WBS hierarchy.

To make the final product more manageable and organized, this large chunk of work is divided into smaller segments known as phases, or deliverables, depending on the type of WBS you’re creating (i.e. deliverable-oriented WBS or phase-oriented WBS, as explained earlier).

Level 2: Phases/Deliverables

The elements of the second level of a Work Breakdown Structure are most often known as phases or deliverables. They will be different depending on the industry and project type.

There is no set number of phases/deliverables a WBS should have at the second level, or any other level. The WBS should contain as many elements as necessary in order to divide the project deliverable into its smallest constituents.

After determining the main deliverables or phases of the project, it’s time to divide each of them into their smaller constituent components, called work packages.

Level 3: Work packages

Work packages are third-level elements of a Work Breakdown Structure, sometimes considered the most important. This is because they represent mid-sized deliverables that are small enough to be manageable, but not so small that they are redundant.

Oftentimes, project managers don’t write the WBS past the third level. If they do, however, they further divide the work packages into activities.

Level 4: Activities

As mentioned above, the activities in the fourth level are not a mandatory part of a Work Breakdown Structure, and whether you include them or not will either depend on the project, or on decisions made by the higher management. 

In the case they are required, they are usually comprised of all the minute activities that need to be completed in order to complete the project work packages. 

Most of the time, these activities are small enough in scope to be performed by a single person.

Level 5: Tasks

The rarely-used fifth, and final level of the WBS are tasks. They are often deemed too small and/or redundant to include. Tasks are a list of items that need to be performed to complete the activities mentioned above.

Why use a Work Breakdown Structure (WBS)?

The Work Breakdown Structure is an indispensable part of the Waterfall methodology, but isn’t best suited for Agile projects. And yet, many project managers choose to do it anyway. 

This is because the WBS is essentially an easy-to-follow roadmap to finishing a complicated project. It offers so many benefits that, even if there are other approaches they like better, project managers still choose it over any other.

A WBS makes it easier to develop a project schedule

Since the WBS already contains 100% of the work that needs to be completed and that work is already prioritized and divided into smaller chunks, half the work for completing a project schedule is already done.

A WBS helps set clear benchmarks and milestones 

Having a visual representation of the work decomposition makes it easier to set milestones and know exactly what’s needed to complete them. It also helps in benchmarking progress against expectations.

A WBS helps identify dependencies

Having a breakdown of all the deliverables or activities “on paper” will help identify dependencies among certain work packages that might influence the project later on. 

A WBS helps identify risks

According to Devy and Reddy (2012), having a well-defined Work Breakdown Structure helps project managers track the work from the smallest deliverables to the level of the entire project.

This makes it easier to detect those small tasks that can sometimes have long-reaching consequences.

A WBS improves team organization and productivity 

A visual representation of work helps fit all the pieces of the project together to help teams understand their exact role in the overall scheme of things and the reason for performing their respective tasks. 

This helps team members understand exactly what lies ahead, when, and why, and motivates each individual to perform their tasks more effectively, improving productivity in the process.

A WBS improves timeline and budget estimates 

Detailed decomposition of work significantly decreases the margin of error when estimating the budget and duration of tasks. 

While working on a larger scale might cause some of the costs and time losses to be overlooked, multiple smaller-scale estimates paint a much more accurate picture of the actual constraints.

💡 Plaky Pro Tip

To help keep your cost estimates in check, you may want to consider using a cost forecasting method called estimate at completion (EAC). Read more about it here:

How to create a Work Breakdown Structure (WBS)

The WBS is the most important element of the Scope Baseline — one of the key documents used to measure the progress of a project. In fact, according to researchers, a poorly constructed, or non-existent WBS is the most common cause of complete project failures.

This is why it’s important to make this visual representation of scope as accurate as possible. 

Here’s how to create a Work Breakdown Structure (WBS):

  1. Determine key objectives — To do this, you must first define the scope of the project and thoroughly understand the intended direction, goals, and stakeholders of the project. All of this, including the main project deliverables, should be documented in the Project Charter.
  2. Decompose elements — Once you have the main deliverables, begin breaking them down (decomposing them) into smaller, more manageable, independent sections. Take care not to duplicate entries and that each entry is small enough to be managed by only one department or person.
  3. Hierarchically arrange elements — Once you have subdivided each deliverable into its simplest components, arrange them into levels going from the largest all the way to the smallest deliverables. Use a coherent coding scheme to number the elements.
  4. Create a WBS Dictionary — Write an exhaustive document thoroughly explaining each item listed in the WBS.
  5. Distribute tasks — Once the WBS is complete, identify the key team members and distribute the work so that each work package is handled by only one team so there’s no activity overlap, and start working.

Tips for writing a Work Breakdown Structure (WBS)

While the way a WBS is created in great part depends on the project manager and the organization they work for, there are a few rules and guidelines that should be followed when creating a WBS. 

Let’s look at each of these in more detail.

Write down everything

Although written in proverbial bullet points, the WBS should include 100% of the work needed to complete the project — no more, and no less. This doesn’t mean that every minute detail should be included in the WBS. But, once you determine to which level your WBS will be decomposed, take care to omit nothing.

Make sure that same-level items are independent of each other

One of the reasons why a WBS has different levels is to make it clear that items on higher levels are dependent on the items directly below them. However, when it comes to items that are on the same level, they should be entirely independent of one another. 

If you find that the completion of one item on the third level of a WBS, for example, depends on the completion of another third-level item, it’s a sign that something has gone wrong, and that you should redo your WBS.

Do not repeat work packages

One hard and fast rule of creating a WBS is that no item on the graph should be duplicated. Doing this creates dependencies between items on the same level and causes mistakes in the duration and cost estimates for the entire project. Not to mention that it breaks the 100% rule mentioned above.

Stick to the 8/80 rule

This “rule”, also known as the 10-day rule, means that once you get to a point in the WBS where each of your items requires no more than 80 hours, or 10 days to complete, you can stop with the decomposition and call your WBS complete.

Now, this is more of a guideline than a rule, but it does help in creating an efficient breakdown of work, so it’s good to keep it in mind at all times. 

Use a coherent coding scheme

Otherwise known as code of accounts, the coding scheme is a necessary part of any WBS. Think of it as numberings for headings and subheadings. 

While it’s not particularly significant for the WBS itself, it’s critical when trying to make sense of the WBS Dictionary.

Helpful tools for creating a WBS

Project managers know that a good project management software makes all the difference when managing a project. This is why 44% of senior executives listed digitalization as their number one investment priority in 2020, recognizing the necessity of digital tools for the future of the trade.

Organizations might be willing to set aside large sums for digital upgrades, but such improvements don’t have to be expensive. 

As previously mentioned, there are fantastic project management software out there such as Plaky, that are modern, free, easy to use, and have all the functionality needed to bring your project management game to the next level.

Plaky can help you organize your teams and tasks, as well as store all your important lists, documents, and correspondence in one place. With this, all the information necessary for creating an immaculate Work Breakdown Structure will be at your fingertips.

Assigning team members to their respective tasks in Plaky
Assigning team members to their respective tasks in Plaky (project management software)

Work Breakdown Structure (WBS) example

Now that we’ve explained the elements, steps, and rules of creating a Work Breakdown Structure, let’s take a look at a simple, three-level example that brings them together.

For the sake of simplicity, we’ll be turning a wedding plan into a phase-oriented project — but the principle is the same for any type of project.

Work Breakdown Structure example in Plaky
Work Breakdown Structure example in Plaky (project management software)

The first level of the WBS is always occupied by the final project deliverable, in this case, the wedding

The project deliverable is then divided into phases on the second level.

The phases are further divided into smaller work packages that are in this case presented in each of the four columns and numbered accordingly. 

For instance, the wedding project is divided into four phases:

  1. Planning,
  2. Preparation,
  3. Execution, and
  4. Closing phase.

The first, planning phase consists of four work packages:

  1. Decide the date,
  2. Decide the venue,
  3. Decide the number of guests, and
  4. Decide the food.

The second, preparation phase has five work packages:

  1. Book the venue,
  2. Create the invitations,
  3. Book a photographer,
  4. Book a caterer, and
  5. Choose a wedding dress.

The third phase, or execution phase, also consists of five work packages:

  1. Gather at the venue,
  2. Welcome guests,
  3. Say YES, 
  4. Have the first dance, and
  5. Enjoy the party.

The fourth and final phase, called the closing phase, has three work packages:

  1. Part with guests,
  2. Gather presents, and 
  3. Enjoy the honeymoon.

This wedding plan is a simple example of a three-tier WBS. After completing each of the work packages defined within a phase, a phase is considered complete. Completing all four phases marks the end of the project.

Conclusion: A WBS makes large projects more manageable

A Work Breakdown Structure is a visual representation of a hierarchical subdivision of all the deliverables or tasks needed to complete the final product of the project.

A WBS makes an enormous project seem significantly less daunting since it breaks it up into many smaller tasks that can be easily managed and performed by smaller teams. 

Along with the WBS Dictionary, the Work Breakdown Structure is the most important element of the Scope Baseline and it’s usually associated with traditional project management approaches. 

However, project managers everywhere like to use it due to its many benefits, most notably, the improved project duration and cost estimation and early identification of potentially problematic dependencies early on in the project.


  • Brotherton, A, S., Fried, T, R., and Norman, S, E. (2008). Applying the Work Breakdown Structure to the project management lifecycle. Retrieved March 15, 2022, from http://citeseerx.ist.psu.edu/viewdoc/download;jsessionid=94FADBCEAF381B24F816E8475201E83A?doi=
  • Devy, R, T., and Reddy, S, V. (2012). Work Breakdown Structure of the Project, Retrieved March 29, 2022, from https://citeseerx.ist.psu.edu/viewdoc/download?doi= 
  • Project Management Institute. (2020). Ahead of the curve: Forging a future-focused culture. Retrieved March 18, 2022, from https://www.pmi.org/-/media/pmi/documents/public/pdf/learning/thought-leadership/pulse/pmi-pulse-2020-final.pdf?v=2a5fedd3-671a-44e1-9582-c31001b37b61&sc_lang_temp=en

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