Understanding Triple Constraint and the Project Management Triangle


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A project allows a team, a company, or any organization to reach a certain goal. Project management provides the guidance, controls, and best practices to ensure that a project starts, moves, and ends on a path of success to achieve an outcome with acceptable quality. But in the real world, this path is full of constraints, challenges, risks, and roadblocks. A project has boundaries and foremost of these is the iron triangle, also called the triple constraints or the project management triangle.

Understanding Triple Constraint & The Project Management Triangle

The Concept of Triple Constraint Explained

Every project has basic characteristics. It has a clear start date and end date. It involves activities that produce something new. But completing a project is not an easy task, as most projects operate within boundaries and constraints, three of which are scope, time, and cost. These three interdependent constraints are inherent in every project, and any adjustment in one affects the other two, as well as the quality of the project and final deliverable.

Triple Constraint

For example, based on a defined project scope, the project manager creates a schedule with a projected end date where the project team produces the final deliverable. From this schedule, the project manager calculates the cost of resources and other expenses needed, then comes up with the equivalent total project budget that the project manager asks the project sponsor for approval. But as the project proceeds, the scope expands because of scope creep. This change in scope affects the schedule, which can lead to missed deadlines. But to keep the same end date, the project team will need additional resources, which will consequently make the project go over its budget.

What is the Project Management Triangle?

The project management triangle is a good representation of the relationships of the triple constraint concept where each side or point of the triangle represents a specific constraint.

Project management triangle


Scope refers to the extent of the project. It defines what is part of the project, its purpose, objective, boundaries, and the work needed to achieve the final deliverable, be it a product, service, or result. Extending the scope when scope creep happens disfigures the perfect triangle so to speak, and the project ends differently compared to the initial plan or vision. This can mean without compensatory adjustments, the project will miss its deadlines, or it will go over-budget because of an extended schedule, or both.


The time constraint is the schedule the project stakeholders agreed to. It is the estimated total amount of time the project team needs to complete all the tasks and deliver the final result. When unforeseen delays during project execution happen, such as additional scope or unavailable resources, the original schedule shifts. To get the schedule back on track, the project team may have to remove some items in the scope or ask for additional budget to get more resources.


Cost refers to the constraints brought about by using or hiring resources for the project. Although a project aims to provide value at the end of its execution, the cost should always be less than the perceived expenses at the beginning. Otherwise, it is not good business. If the sponsor reduces the project budget unrealistically, then the project team can only do so much tasks at a given time. They will probably miss the deadline. Or they can still meet the deadline but end up neglecting some of the project requirements, either way affecting the end result of the project.

The Iron Triangle as a Project Management Tool

Knowing about the triple constraints of project management and how it affects project delivery and success is one thing; using it to your advantage is another. One way to benefit from it is to use it as a guide to know the stakeholders’ priorities and manage their expectations.

Scope as priority

If scope is the highest priority for the client and stakeholders, they can request changes or additions at any time in order to arrive at the exact result they wanted. The project manager should also make it clear to the client that they have to remain open to the idea of a more flexible schedule to accommodate the changes they want. Also, additional scope means additional time and/or resources, which will increase project cost. On the part of the team, the project manager should explain clearly that with scope as priority, they can expect additional work as the project progresses.

Time as priority

If schedule is the highest priority, it means that no matter what, the project needs to end at the set completion. The project manager needs to explain to the client and sponsor that sticking hard to the deadline can result in either an increase in cost for additional resources or a cut back on the original scope. Any changes in the scope can also affect the end quality of the final deliverable, so the project manager needs to track changes, watch metrics, and test work items in addition to tracking time.

Read more: Best Time-Tracking Software

Cost as priority

If cost is the highest priority, this means the project team needs to operate strictly within the allocated budget. The project manager needs to communicate to clients and sponsors as often as possible and convince them that working with limited resources may requirement an adjustment in the project schedule, scaling back the project scope, and agreeing upon a reduced quality of the final deliverable.

Limitations of Using the Iron Triangle

As the field of project management evolves, some experts see a limitation in the iron triangle. Some revised it to be a management constraint triangle with financials, stakeholders, and resources as the constraints. The PMBOK suggests additional constraints that include quality, benefit, and risk in addition to the original triangle constraints. Whether three or more, project constraints will always exist so project managers need to have all the tools they need including project management software. Also, they need to make it clear to clients and other stakeholders that any change in one constraint will certainly affect the others. So the project manager needs to communicate that it is really all about trade-offs.

Constraint trade-offs

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