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Assumptions vs Constraints

Assumptions vs Constraints

If you enjoyed reading this post, check out all of our post on PMP Concepts Learning Series.

Designed to help those that are preparing to take the PMP or CAPM Certification Exam, each post within this series presents a comparison of common concepts that appear on the PMP and CAPM exams.

Assumptions vs Constraints

Assumptions and constraints are both noted in your project documentation and are revisited throughout your project life cycle.


Assumptions are those things that we believe to be true based on our knowledge, experience, and/or information provided by our team members or other stakeholders.

It is important to document the project assumptions (including those considered when estimating the project’s scope, schedule, and costs) so that as the project progresses the PM is able to verify and validate the accuracy of those assumptions and capture lessons learned.

Assumptions also feed into risk management, as each assumption can be tested by asking, “if this assumption was false, would it have an effect on the project?”. If so, the assumption should be documented as a risk.


Constraints are limitations placed upon the project that the project manager and team must work within. The most common constraints cited in project management are: scope (what the project needs to deliver), schedule (how much time do we have to deliver that scope), and cost (how much funding has been allocated). This is known as the “triple constraint” or “iron triangle” of project management.

In addition, the project may be constrained by quality requirements, resources, and risk tolerances.
The constraints are related in that if one constraint changes, there will most likely be an impact on the other constraints. The constraints also dictate the perceived quality of the project.


Your company has been hired to build a vacation cabin for Mr. and Mrs. Jones. The project is constrained by a budget of $120,000, a schedule of 3 months, and the cabin needs to have three bedrooms and two bathrooms. In addition, the cabin must pass all city inspections to allow for occupancy (a quality constraint).

Your assumptions include: funding will be provided prior to the start of construction, you and your team will have unlimited access to the building lot, and the materials requested are available for immediate delivery.

If you deliver the cabin but it is late and cost twice as much as expected, Mr. and Mrs. Jones will most likely not feel the project was high quality, although the product (the cabin) is.


Constraints and assumptions are both important aspects of project management and project planning. Both should be documented and analyzed throughout the project and variances analyzed as part of the project’s lessons learned.

See all posts in our PMP Concepts Learning Series

1 Comment

  1. Roosevelt Woolfork on August 22, 2018 at 6:46 pm

    This was Great Ms. B. Thanks a million.

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