What Is the Project Management Triangle?

Project management triangle definition

The project management triangle, also called the triple constraint model or the iron triangle, is a visual representation of the relationship between the scope, time, and budget constraints in project management.

Scope: Scope refers to the size of the project in terms of the deliverables and tasks that must be completed to achieve the project’s goals. The scope might change if stakeholders decide mid-project that they want to adjust a product or add another product entirely. Project scope might also include factors like complexity, the number of deliverables, changing requirements, and adding features.

Cost: Project cost is the total amount of money required to complete a project. This is also called the budget. Costs might include salaries for employees and money for equipment, tools, office space, and other resources. Adding new members to a team or increasing the time it takes to complete a project can impact cost.

Time: Time is how long it takes to complete tasks in a project and the project itself. This constraint is also called the schedule. An expanded scope can increase timelines. So can a decreased budget—for example, if a team member is removed from the team due to budget constraints, it can take longer to complete a project.

The relationship between these constraints determines the quality of the project. Altering one constraint will mean adjusting one or both of the others to maintain the quality. Project managers must oversee all three of these constraints to complete a project successfully. 

Project management triangle example

Let’s say that you need to expand the scope of a project. This might mean extending the original schedule of the project, or increasing the budget in order not to affect the quality of the output. Likewise, shortening the schedule to meet an earlier deadline might mean increasing the budget or tightening the scope. If you need to reduce the budget and timeline without changing the scope, then the triangle might have to shrink — meaning the quality of the product might be reduced.

Some models show an enhanced project management “triangle” with six constraints [1]:

1. Scope

2. Cost

3. Time

4. Benefit (sometimes called “resources”)

5. Risk

6. Quality

This model is sometimes depicted as a six-point star made from two overlapping triangles.

Read more: What Is Scope Creep? Keeping Your Project Focused

What is the project management triangle used for?

The project management triangle is a useful concept for project managers. It offers several benefits, including:

Seeing how changing one constraint affects other constraints

If you change the scope of a product you’re hoping to launch, you know that either the budget needs to increase or the timeline needs to be extended (or both).

Mitigating risk

Say your project to launch a new piece of software has a hard deadline, and you’re worried your engineers will fall behind. You can ask stakeholders for a contingency budget, just in case you need to hire another engineer to help complete tasks.

Read more: How to Manage Project Risk: A 5-Step Guide

Clarifying priorities in a project

Does your project have a hard deadline, a strict budget, or specific deliverable requirements? Knowing this can give you a better idea of what a successful project will look like.

Managing the project management triangle

Here are concrete ways to balance the constraints of the project management triangle. 

Communicate with stakeholders.

Speak with stakeholders to know what constitutes acceptable change and which constraints should be prioritized. Is the deadline immovable or the budget strict? This will give you an idea of how the project can adapt should changes become necessary. This is a crucial step in the initial stages of the project, but frequent communication should happen throughout the project as well.

Establish risk management processes.

Planning for risks should be a step baked into your project management process to prevent scope creep and stay within budget and on schedule. Identify risks, then establish a plan to mitigate each. If you’re looking for more detail, read about how to manage project risks.

Create change management processes.

Change is often inevitable. Having a change management process in place creates a structured way for changes to be approved or rejected. This ensures the team is aware of changes as they happen and how they impact the project. This can also reduce scope creep.

Choose a methodology based on constraints.

You might opt to adopt a project management methodology based on the constraints you face. Projects that face strict constraints are often managed through Waterfall-type approaches. If you need more flexibility, an Agile method like Scrum might be more fitting. Projects where inefficiencies need to be minimized as much as possible can benefit from a Lean approach.

Use project management software.

Having the right tools in project management can help you manage the three constraints by improving visibility, encouraging stakeholder communication, managing resources, scheduling and assigning tasks, and sending project alerts.

Here are some software tools to investigate:

• monday.com

• ClickUp

• Asana

• Smartsheet

• Airtable

• Teamwork.com

• Wrike

Read more: 12 Project Management Methodologies: Your Guide

Get started in project management with Coursera

Taking online courses can be a great way to learn more about the project management triangle and build other skills for this field. Check out the Google Project Management: Professional Certificate to learn project documentation, how to communicate with stakeholders, use Agile approaches, and more.

Frequently asked questions (FAQ)