The Iron Triangle of Project Management

Balancing Your Budget, Scope, and Schedule

(Also known as The Triple Constraint of Project Management.)

Learn how to deliver projects within the "iron triangle."

You're managing the implementation of a new reporting system for your organization. As your project progresses, things happen differently from how you'd planned. You find that you need extra computer hardware, and some tasks have taken longer to complete than you originally predicted.

To get the tasks completed on time, you consider recruiting more contractors. But, to do this, you'd have to take other costs out of the project's budget. You think about not buying the extra computer hardware that you need, however, this would mean changing the project's scope, so that some functionality isn't delivered.

In many projects, the budget, scope and schedule are closely linked. Changes to one of these three key constraints will most likely affect the others, or impact on the quality of the project.

This article examines the relationship between the three constraints of budget, scope and schedule, and looks at ideas and tools for helping you deal with the issues that can affect this relationship.

The Iron Triangle

The project mandate and project charter identify the project's objectives. At the core of these documents is a requirements statement that says what the project needs to deliver. This includes a definition of what is in and out of scope for the project. It also establishes the project's deadlines and its budget.

These constraints of scope, budget, and schedule are known as the "iron triangle" (see figure 1).

Figure 1 – The Iron Triangle of Project Management

The Iron Triangle of Project Management

Original diagram in the article, "What is Project Management?" Reproduced with permission of the Association for Project Management.

These constraints are considered an iron triangle because you can rarely change one constraint without also impacting the others. The way that you deliver the project within these constraints impacts the quality of the project's outcomes, either positively or negatively.

For example, suppose your project mandate is to launch a new standalone IT system. The design phase has overrun significantly. You could consider several options:

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