Assumptions and Constraints in Project Management

Fahad Usmani, PMP

July 29, 2024

Today, I will explain the project assumptions and constraints to you.

Let’s start with a real-world example.

Suppose you want to go shopping at a mall that takes one hour to reach by car. You assume you would leave your home around 6:00 p.m. and reach the mall by 7:00 p.m.

This is an example of an assumption you believe to be true.

What about constraints?

In the shopping example, you can think of two. The first constraint is money. If you have 500 USD, that’s all you can spend on this shopping trip. The second constraint is the mall’s closing time, i.e., 10:30 pm. This means you cannot continue your shopping after that.

Likewise, projects also have assumptions and constraints. You must understand and manage these factors to complete your project successfully.

Let’s dive in.

Project Assumptions and Project Constraints

Project assumptions and constraints are identified at the beginning of the project. They are refined and re-analyzed throughout the project life cycle and are key to many project management processes in the PMBOK Guide.

You don’t manage assumptions and constraints like requirements or risks. However, documenting them helps to protect you from future risks. You should outline your project’s assumptions and constraints in the scope statement.

Project Assumptions

An assumption is what you believe to be true without any evidence. It refers to expected events or circumstances during your project’s life cycle.

They fill gaps in knowledge and help in forecasting and planning. You make assumptions based on educated guesses, past experiences, industry standards, or logical deductions. They are necessary to move forward with planning when complete information is unavailable.

Assumptions may not end up being true. They can sometimes be false and may negatively affect your project.

Let us reconsider the earlier example. You assumed it would take you one hour to reach the destination. What will happen if you are stuck in traffic and can’t reach the mall on time?

Your assumption turned out to be false. Your shopping is at risk because you don’t have as much time as planned.

This can also happen to your project.

For example, you assumed you could get the necessary equipment whenever needed. However, due to shortages or supply-chain problems, you couldn’t get it when the time came.

Now you are in a difficult situation.

Assumptions play an essential role in developing a risk management plan. Therefore, you must analyze each assumption and predict its impact.

Project Assumptions Examples

The following are a few examples of assumptions in project management:

You will get all the resources you need.
During the rainy season, cheap labor will be available.
All relevant stakeholders will come to the next meeting.
Your team members have all the required skills.
All equipment is in good condition.
The supplier will deliver consumables on time.
Market conditions will remain stable throughout the project.

You can see how your project will be radically affected if any of the assumptions above turn out differently.

Project Constraints

Project constraints are limitations on a project, such as the budget, schedule, or resources. These are definitive factors that the project team must work around. The PMBOK Guide recognizes six project constraints: scope, quality, schedule, budget, resources, and risk. Of these six, scope, schedule, and budget are known as triple constraints.

These constraints are defined at the beginning of your project, and you must work within their boundaries.

A constraint can be of two types:

Business Constraints
Technical Constraints

Business Constraints

Business constraints depend on the state of your organization. High-level constraints, like time, budget, and resources, are defined when the project starts.

Changes to these constraints are rare, and the project management team has to work within them.

Technical Constraints

Technical constraints limit your design choices. They are fixed, and any change to the technical specifications can affect your project planning.

For example, let’s say you’re constructing a pipeline. According to the design, the pipeline should withstand a certain amount of pressure; this is your technical constraint, a fixed reality.

Every project has constraints. Therefore, you must identify all of them and develop your plan accordingly. Constraints are outside your control and imposed by clients, organizations, or government regulations.

Project Constraints Example

A few examples of constraints are:

You must achieve the first milestone within one month.
You have to work with the available resources.
You will only have two site engineers.

Assumptions Vs Constraints

The following are a few differences between assumptions and constraints:

Assumptions are believed to be true, while constraints are true.
Assumptions are good for the project, while constraints are not always favorable to the project objective.
If assumptions become false, it is bad news for the project. However, if constraints are false, it is positive.

Assumptions and constraints play a vital role in the planning process and are the foundation of your project management plan.

Any assumption is a potential risk for your project because it can cause trouble if it is incorrect. Your risk management plan heavily depends on assumptions and constraints, and failing to identify any of them can affect your project.

Roles of Assumptions and Constraints in Project Management

Assumptions and constraints are essential in project management, and impact planning and execution differ.

Assumptions allow you to make informed decisions and create realistic plans. They help in estimating timeframes, costs, and resource requirements. However, being only assumptions, they are risky. If an assumption proves incorrect, it can negatively affect your project objectives.

You can manage assumption as follows:

Document Assumptions: Clearly state and document all assumptions during the planning phase.
Validate Assumptions: Regularly review and validate assumptions to ensure they remain accurate as the project progresses.
Plan for Contingencies: Develop contingency plans to address potential issues if assumptions are incorrect.

Constraints define the project boundaries, set parameters, and help with realistic expectations. Because they are non-negotiable, the project plan must accommodate them from the outset. Understanding constraints helps prioritize tasks, allocate resources efficiently, and make trade-offs when necessary.

You can manage constraints as follows:

Identify Constraints Early: Recognize all constraints during the initial planning phase.
Communicate Clearly: Ensure all stakeholders know the constraints and their implications.
Monitor and Adjust: Continuously monitor constraints and adjust the project plan to stay within the defined limits.

Summary

Assumptions and constraints are an important part of your project. They need to be identified, controlled and monitored continuously.

An assumption is a condition you think to be true, and a constraint is a limitation on your project. Assumptions must be realistically analyzed, while constraints must be identified throughout the project lifecycle. Managing assumptions and constraints is necessary to complete your project with minimal obstruction.

Assumptions and Constraints are important concepts from a PMP exam point of view.

Fahad Usmani, PMP

I am Mohammad Fahad Usmani, B.E. PMP, PMI-RMP. I have been blogging on project management topics since 2011. To date, thousands of professionals have passed the PMP exam using my resources.

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