Skip main navigation

The iron triangle

A key part of the initiation phase of the project life cycle is understanding the triple constraints of time, scope and cost – the iron triangle.
The iron triangle represents the three project parameters that must be managed by Project Managers in project delivery. Success in the management of a project has been traditionally associated with the ability of the Project Manager to deliver in time, cost and quality. These three factors, commonly called the triple constraint, are represented as a triangle. Each constraint forms the vertices with quality as the central theme. Projects must be delivered within cost. Projects must be delivered on time. Projects must also meet customer quality requirements. Time represents the date that the project needs to be completed by. Cost is defined by the overall budget and quality ensures the project is completed to its agreed specifications.
The three constraints are linked together, meaning you cannot change one without the other. The Project Manager must overcome these constraints whilst the project is underway, striking a balance between the parameters to ensure the quality of the project isn’t compromised. This requires a trade-off. For example, if you were delivering student accommodation to a deadline for the next academic year and your project was running behind schedule, you could spend more money and reduce the quality specifications to hit the deadline. Each project is unique and will often need to have the three project parameters adjusted over time. This will all depend on the client and their priority of objectives.
Whether its more important to finish on time, on budget, or achieve the right quality. To overcome the restraints of the iron triangle, you, as a Project Manager have many tools and techniques at your disposal to supervise and control the project from the start to the completion.

The iron triangle is a project management tool that shows how three factors can be linked. If two of the parameters (ie points on the triangle) change, it affects the third. Within project management, these parameters are typically time, cost and quality. The video above explains this concept.

The iron triangle consists of time, quality and cost

Once a project manager has committed to a project, the cost, time and quality can seldom be compromised without renegotiating project terms. In every project, a change in one or more of these things will have predictable impact on the others. For example:

Faster time + increased quality = higher cost

Faster time + lower cost = lower quality

Higher quality + lower cost = slower time

Essentially, we can increase two of the three parameters, but it will come at the expense of the third. This is why sometimes the iron triangle is called the triple constraint – these three parameters constrain every project.

This article is from the free online

Project Initiation

Created by
FutureLearn - Learning For Life

Our purpose is to transform access to education.

We offer a diverse selection of courses from leading universities and cultural institutions from around the world. These are delivered one step at a time, and are accessible on mobile, tablet and desktop, so you can fit learning around your life.

We believe learning should be an enjoyable, social experience, so our courses offer the opportunity to discuss what you’re learning with others as you go, helping you make fresh discoveries and form new ideas.
You can unlock new opportunities with unlimited access to hundreds of online short courses for a year by subscribing to our Unlimited package. Build your knowledge with top universities and organisations.

Learn more about how FutureLearn is transforming access to education