The Project Management Triangle (Iron Triangle) & Its Elements Explained

Friday, July 29, 2022
Michael Scheiner

Have you recently come across the concept known as the iron triangle of project management and scratched your head? This article is going to explain everything you need to know about this iron triangle. 

It will go into detail about what is the project management triangle and give some examples of how to apply it. The article will also examine some variations to the iron triangle of PM, and answer some frequently asked questions.

So, if you‘re ready to get your PM knowledge triangulated to the max, adjust those reading specs, and let’s get to the elements of the project management’s iron triangle of triple constraints. 


What is the project management triangle?

The project management triangle is also known as the project management golden triangle, the iron triangle of project management, and the constraint triangle. It is an important aspect of project planning methodology, especially with such systems as agile PM.

When you refer to it as the constraint triangle, you get a good idea of its function. As everyone knows, a triangle has three sides, and each side of the PM triangle represents one of the three constraints that a project manager must be aware of when trying to attain top project success. This triangle metaphor is why the term triple constraints of project management exists. 

We will, of course, outline in more detail what each of these three project constraints is below, but to quickly name them here, they are: the amount of time, the project cost, and the project scope constraints.

The idea of a triangle is balance, meaning each side touches and supports at its two opposite ends the other two sides. What this means is that there is a relative and dependent relationship between each constraint with both other ones.   

A high-quality successful project depends on respecting the tradeoffs between each of these three constraints and dependencies.

Why is the iron triangle project management model important?

The PM iron triangle model is quite important. This is because the iron triangle concept allows managers and project team members to focus on delivering the best quality of the project without running into unexpected problems. 

Such problems include scope creep, which refers to the situation when the team, clients or stakeholders constantly want to add things to the project and increase the scope of a project without factoring in as part of their decision-making how this might affect the project schedule or the project budget.

Likewise, if a stakeholder wants to cut the budget due to unforeseen cost constraints, the iron triangle avoids problems regarding the backlog by limiting the scope of the project to match the new lower project budget. 

Finally, if the lifecycle duration of the project changes, respecting the tradeoffs in the iron triangle of constraints allows the project team members and managers to adapt the cost and the scope to a longer or shorter timeframe. 


What are the three elements of the project triangle?

In this section, we’ll break down in further detail each one of the elements in the project triangle of triple constraints. The project triangle consists of:

  • Scope

  • Budget

  • Schedule

Project scope

The scope of the project is often laid out in the early stages of project planning, well before project execution. This is the part of the project where you spell out the scope in a project backlog which details the aims of the project, the project’s goals, and what the project delivery in the end promises to deliver. 

If we’re talking about a product, whether a manufactured good, a digital SaaS, or a service, the scope details all the functionalities the deliverable will be able to perform. Implementing a project with a clear project scope makes planning and implementation much simpler.

Project cost

When we are talking about costs, we are talking about budgets, and this is often something that is crucial for the successful completion of a project. Projects cost money, and stakeholders have a strong interest in seeing projects come in on budget, and not over budget. 

Project costs will include first and foremost materials, and then labor which is always tied to employee time management. Other budget elements are overhead like real estate and server space, as well as money put aside for outsourcing to freelancers and other independent contractors. 

Project schedule

Time constraint management is key to maintaining a balanced project triangle system within the triple constraints. Start dates and end dates are important elements here, as are milestones. 

Many project managers prefer to use software and templates for scheduling, and these regularly include the Gantt chart which is ideal for milestone planning and other time-sensitive workflows.

Project quality

Quality is not one of the standard triple constraints of the iron triangle. More often, the quality of deliverables is placed in the middle of the triangle, meaning that cost, time and scope are what form the bordering outline for overall project quality. 

However, there are some managerial styles that prefer a square to a triangle and to include quality as a fourth constraint. But this is not for most managers.


How to use the iron triangle of project management

Let’s break down how to use the triple constraint schema of project management. 

Understand your customer’s requirements

Everything begins with knowing what the project stakeholder or client wants out of the project. First and foremost is the ultimate quality of the product. Shortly afterwards, it is time to hammer out the constraints: What is the scope, what is the budget, and what are the deliverable deadlines. 

Get it in writing in a project charter or product backlog. Decide if you are going to use project management software, and which tools specifically: for example: Gantt charts, Kanbans, schedulers, accounting software.

Be adaptable to constraint changes

Later below, we’ll give some concrete examples of how the triple constraints of the PM triangle function. Here we’ll just emphasize the point that when any one of the three constraints changes, you must be ready to make further changes in either one or both of the other constraints in near real time. 

A new deadline that’s closer means maybe cutting the scope; a sudden increase to your budget means a larger scope; scope changes can affect both cost and timing.

Feedback, analysis and future planning

Every time a project team works within the triple constraints of their project and makes adaptations in real time, those activities generate data which should be analyzed. This is a great field test for knowing more precisely how a change to a budget or deadlines affects not only the end result, but the project process and all the project team members' work morale as well. 

This way, when planning the next round of deliverables or a whole new project, these insights from previous project constraint adaptations will inform the planning process going forward for less risk and uncertainties.


Project management triangle example

Let’s put the project management triangle into action.

PM triangle example 1: Event planning

Say you are an event planner, and the project is a large fundraising gala. The client gives you a budget of $100,000. The gala will be in exactly 3 months. And the scope of the event includes: 1,000 guests, a reception hall in a five-star hotel, a band, and a full sit down dinner with prime rib and champagne. 

Then, the client must slash the budget. This means the money constraint should affect the scope. You can relocate to a cheaper reception hall, swap out a band for a DJ, or change from a sit-down meal to hors d'oeuvres only.

  • Budget goes down

  • Scope goes down

PM triangle example 2: Starting a new department

You are in a company that in the past had always outsourced marketing, but now the company wants to open up their own internal marketing department. The company wants this done in one year, and is ready to invest $250,000. The scope of this project includes: an office renovation and hiring and onboarding 15 new employees as well as equipping them with computers and supplies.

Then, the company decides it needs this new department much sooner than one year. They want it up and running within 4 months. This means the time constraint has changed. You can increase the budget to hire more builders to finish the renovations faster, as well as hire more recruiters to staff up the department quicker. Or, you can decide to change the scope, have fewer new employees, and simply cram more desks into the office rather than renovate.

  • Timeframe goes down

  • Budget goes up

  • Scope goes down

PM triangle example 3: Software upgrade

A company released an app one year ago and ever since then it has been having issues and receiving requests for bug fixes. Now it is time to totally upgrade the app and release a version 2.0. All the bugs will be fixed, and the company wants to add several new features. The company plans a 3-month project to achieve all of this, and budgets $15,000 to be spread over a dedicated software team of 5 coders and programmers.

Then, halfway through the project schedule, the bosses decide they also want to give the front-end look and feel a whole new makeover to adapt to changing aesthetic preferences. When a project scope increases such as this, you could increase the budget to hire more developers to get the same job done in the same timeframe, or extend the project schedule so that the same number of employees can finish all the tasks on budget. Or you can do both.

  • Scope goes up

  • Budget goes up

  • Timeframe goes up


Variations of the project management iron triangle

There are indeed some variations of the standard iron triangle. Let’s take a gander at a few of those.

The iron square of project management

This concept was touched upon briefly before. The idea is simple. Instead of three constraints with quality being the central element, quality gets demoted to another constraint, making the previous three-sided figure now one of four sides. How quality differs from scope is not 100% consistent and some managers may think about these concepts differently.

The project management star

The figure in question here is the hexagram or 6-sided star, formed by placing one triangle upside down against another. Instead of placing the constraints on the sides of the triangle, there are 6 constraints placed at each point. They are: schedule, risk, resources, scope, budget, quality. What’s more, the two triangles represent different kinds of constraints, with the first one being for input/output and includes scope, cost and time; while the other being for the project process and includes risk, resources and quality.

The golden grid of project management

The shape of this is a diamond, imagine two triangles reflecting one another across a horizontal axis. The bottom, upside down triangle refers to the project efficiency, and covers something close to the iron triangle, with each point being: cost, time and quality. The top, upright triangle refers to the project effectiveness, and includes as its points: organizational value, end-user impact and future capability.


Is there any iron triangle software that allows use of this concept?

There are indeed many great tools to help plan, manage and execute projects. While there does not seem to be any one specific vendor that specializes in the iron triangle of project management constraints, it does not take much effort to use the various SaaS to your advantage when being aware of the tradeoffs between money, time and scope.

Some of the best project management software offers tools to help with scheduling like Gantt charts and deadline notifications, budgeting and accounting, and task management using things like Kanban boards. 


Our conclusion

When discussing the project or program management triangle, one should be aware that this concept has been thoroughly included as a project management concept by the Project Management Institute—or the PMI as the cool kids call it. 

In the PMI’s Project Management Book of Knowledge, aka the PMBOK Guide, they not only lay out the basics of the iron triangle, but nowadays also include some variations and criticisms to this model. 

Ultimately, when a project, as considered via its constraints, is planned and executed appropriately, bearing in mind tradeoffs and adaptations, managers and project teams will be better equipped to deal with things like project scope creep, going over budget, or missing milestones and deadlines.

Remember, tradeoffs are the name of the game here. You can’t cut costs without keeping your scope intact within the same timeframe, and you can’t speed up a project with the same budget and scope. Those are some serious horse-sense project management tips, no matter which way you break it down. 

A hearty thank you, dear reader, for completing this article front to back all about the relationships among the triple constraint variables of project management, otherwise known as the scope time cost triangle. 


PM triangle FAQs

What is at the center of the project triangle?

The center of the project management triangle is quality. This means that the quality of a project will always be constrained by the three walls of the PM triangle which are cost, time and scope. To maintain high quality, managers must make tradeoffs whenever one or more constraints change.

Which goal is shared by all three components of an iron triangle?

The shared goal of all three elements of the iron triangle of project management is to deliver the product with the level of quality expected by the customer or stakeholder, fulfilling all its chartered functions, and doing so within the project budget and on time. 

What are the three legs of a project triangle?

The three legs of a project triangle are cost, scope, and time. In other words, every project is constrained by its budget, by its deadlines, and according to the scope of functionalities the end result promises to perform. In the middle of the project triangle is quality.