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Project assumptions: What they are and why you should care 7 min read
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Project assumptions are part of every project management cycle. Project managers assume that they’ll have the appropriate budget and talent to complete the project on time.

The fact of the matter is that assumptions can be proven wrong at any time. That’s why it’s essential for project managers to have a deep understanding of what project assumptions are and how to properly identify them during each phase of planning a project. Learn more about project assumptions and why they’re so important, and discover how can help you initiate and execute projects successfully by managing project assumptions.

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What are project assumptions in project management?

According to the Project Management Institute, the definition of a project assumption is “any factor relating to a project that is considered to be true, real, or certain — without any empirical proof or demonstration.” In other words, project assumptions are simply the things you assume to be true for your project’s success.

Naturally, these assumptions will vary with each phase of the project lifecycle. What’s more, since these “things” you assume to be true may or may not actually occur, project assumptions will always come with inherent risks.

Your project assumptions can reflect many different aspects:

  • You assume your team will complete milestones according to schedule
  • You assume suppliers will deliver the right items on time
  • You assume that your employees are capable of completing necessary tasks
  • You assume weather or acts of God won’t interrupt your progress
  • You assume costs won’t change throughout the course of the project

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Why are project assumptions important?

Realistically, it’s impossible — and irresponsible —  to plan a project without making assumptions. False assumptions without backup plans can hinder your project at any phase of the project management lifecycle or impact the quality of your deliverables.

This is why project assumptions are so important — because it’s impossible to foresee every variable within a project from initiation to completion.

The most important thing to understand about project assumptions is that they’re just that—assumptions, and with assumptions come risk. In the project planning process, identifying these assumptions is vital to planning for potential risks that could affect your schedule, budget, or other aspects of the project.

For example, your resource allocations will undoubtedly align with the assumption that you’ll have the necessary resources — talent, funds, materials, etc. — available to you as needed. But it’s important to remember that resources may run out, so consider your assumptions in the initiation, planning, and execution phases to prevent the negative impact they may have should your resources run out.

What is the connection between project constraints, dependencies, risks, and assumptions?

For many project managers, the distinctions and connections among project assumptions, constraints, dependencies, and risks aren’t always so clear.

Here’s a quick overview:

Constraints are the limitations that you and your team must work within. Project constraints typically include the following:

  • Your budget
  • Your timeline
  • Your resources

Read more about project constraints here

Dependencies are any tasks or activities that rely directly on the completion or initiation of another task or activity. They often arise as a result of project constraints. For example, let’s say you have a task that needs to move to the next phase but can’t without the approval of the client or a stakeholder. This next phase would be the dependency.

Risks are any unexpected events that can crop up and affect your project. Risks don’t always have to be negative, especially if you’ve identified your assumptions appropriately and made a plan for their occurrence.

With these definitions in mind, let’s look at how to use project assumptions to move effectively through the project management life cycle.

Best practices for managing project assumptions

When it comes to managing project assumptions, you’ll want to follow these best practices:

Assess every potential assumption

The phrase “I think” will occur left and right during the initiation and planning phases of the project. Consider everything that follows “I think” to be an assumption, make a list of them, and then narrow that list down to the most realistic assumptions.

Be sure to view every assumption with an appropriate amount of skepticism, and think about the likelihood of it happening, as well as what the realistic consequences of each assumption would be. Then think about how you can mitigate those consequences.

Integrate the assumptions

Once you’ve identified and assessed the potential assumptions throughout the project’s future life cycle, you’ll need to incorporate them into your project planning.

This means including assumptions about the following:

  • All planned tasks
  • Each point within the project’s timeline
  • The overall budget
  • Your resources
  • Your team members

Maintain control

Since assumptions can potentially hinder your project, you’ll need to remain vigilant in monitoring your assumption integrations. If you don’t monitor your assumptions throughout the life of the project, you won’t be able to enact your contingency plans where appropriate. This can easily done through regular meetings with team members and by consistently monitoring project metrics.

Do a post-project review

Once the project is complete, it’s a good idea to review the assumptions and your process for evaluating them as part of a post-project review.

This will allow you to gain unique insights for the next project as you’ll get a full view of how the project went, what went wrong, and which contingency plans worked best. Your your post-project review should include:

  • Project summary
  • Team members and responsibilities
  • Expectations and outcomes
  • Notes on how your project transitioned from phase to phase
  • A detailed summary of project budget and expenses
  • Project milestones, schedule, and completion dates
  • Recommendations for future projects

Find post-project review templates and other tools to complete your review on

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Managing project assumptions with

See the negative impact of your project assumptions with Utilize tools to create workflows for task management, productivity, and teamwork to gain a better understanding of your assumptions and build a contingency plan for associated risks.


You can use as a project management tool to create workflows, productivity, and teamwork, which will help you see how project assumptions could negatively impact your project’s completion and proactively avoid those pitfalls.

With Work OS, you have a visual representation of your project and the tools to manage it in one place. This makes it super easy to monitor a project’s overall health and the integrated assumptions because everyone has access to the same data and processes.

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Understand Project Assumptions and Plan Ahead to Mitigate Risks

There’s potential to encounter project assumptions at every stage of the project management life cycle.

The only way to mitigate the potential damages of making assumptions is to identify what could happen instead. This helps to implement contingency plans for the consequences, and use what you learned to prepare for the next project.

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