Project management, in the world of PMBOK, used to talk about the triple constraints.

For those using PMBOK, the label “triple constraints” was everywhere.

If you do a search on the web on “Triple Constraints”, you will find numerous articles on the subject.

The triple constraints were:

  • Scope
  • Time
  • Cost


The label “Triple Constraints” refers to the art of balancing scope, time and cost in managing a project.  The three elements are connected, in the sense that if you modify one, you also have to modify at least one of the others.  As an example, if the scope is increased, then either the project will require more time, or cost more (using more resources, overtime, etc), or both.

The model provided a logical framework to discuss these key variables and how they relate to each others.  And it is easy enough to understand.  And it was also good for those who like triangle, since it is so often shown with a triangle image.

And then came PMBOK, 4th Edition, which changed the concept from the triple constraints to the competing constraints.

PMHut has this one on the change to the concept of the competing constraints.

The PMBOK and the changes to the competing constraints

PMBOK still has the notion of balancing the constraints as part of project management.  However, instead of referring to the triple constraints, it now discusses “balancing the competing constraints” (PMBOK, 5th Edition, p. 6).  It then lists the following 6 constraints (while specifying that project constraints are not limited to only those).

  • Scope
  • Quality
  • Schedule
  • Budget
  • Resources, and
  • Risk


The relationship among these is still the same: if one factor changes, at least one other factor will likely be affected.  It is just that the concept has more variables and is more complex.  Hopefully, the use of more variable will many it more useful and more realistic.

I find it interesting that the use of triple constraints seems to remain very in use in project management. I guess it was easier to explain the triple constraints to clients, project sponsor and stakeholders. It is still very much in use that many others are trying to find new ways to represent the competing constraints using triangles.

Which is why we have this title for this article:

Have you adapted your communication and documentation to the concept of the competing constraints?

After all, it is important to keep our project management knowledge, tools and techniques current.

I wonder what PRINCE2 is saying on project constraints?