What are the Iron Triangle Constraints of Project Management?


Project managers often have to create a balance between different factors to ensure quality project delivery. One concept that perfectly captures this reality is the iron triangle of project management constraints. In this article, we will review the concept of iron triangle that helps in successful project outcome.

What is Meant by Iron Triangle?

The iron triangle model was introduced by Dr. Martin Barnes in 1969. The constraints were considered iron since a project manager could not change one constraint without affecting the other. The original model was derived from a waterfall approach to product development.

The three main constraints of the iron triangle model include the following.

  • Scope
  • Budget
  • Time

The above constraints affect the quality of the project delivery. If you change any one of the constraints of the iron triangle, the others are affected. The aim of the iron triangle was to provide project managers the required information for making the trade-offs that help in quality product delivery.

For example, if the scope of a project changes, the time and budget will be affected. If the scope is increased, it will result in an increase in the budget and time as well. Similarly, if the budget is increased or decreased, it will affect the scope and time of project completion. The same is the case with time constraints.

The Purpose of Iron Triangle

The main purpose of theiron triangle is to ensure quality improvements. The project managers should be cognizant of the relationship between different constraints. The iron triangle model helps the project manager know how different constraints affect the quality of the project outcome.

Knowing about the constraints can help in making more effective decision regarding the project. It will allow the project manager to more efficiently allocate the resources that result in optimal project outcome satisfying the requirements of the customer.


Project managers need to carefully manage the constraints of the project. This will have an influence on the quality of the project. An effective management of the project constraints will lead to realistic expectations about changes to the project outcome.

Regardless of the different approaches used when managing a project there is no right and wrong way. A good manager will make use of efficient planning to optimize the quality of the project. The quality of the project outcome will improve if project managers balance the constraints using the iron triangle model.

The important thing is to realize the trade-off between different constraints to reach the project objective. An online collaboration software can help project managers to better manage project constraints. The project management software can help in simplifying complex projects and ease the task of managing people, time, and cost. What’s more, you can easily modify the scope as well using the work management software.