What Are the Triple Constraints of Project Management?

Wednesday, June 29, 2022
Michael Scheiner

It’s said that every project is constrained by 3 important factors. But what are the triple constraints of project management in actuality? 

In this article, we’ll go over what knowledge of PM constraints is meant to help with. Then we’ll break down the 3 project constraints themselves.

Afterward, we’ll demonstrate why these triple constraints of project management are important, give a brief history of the triple constraint theory, and show examples of the current usefulness of being aware of the three project constraints.


What are the triple constraints of project management?

Having a solid understanding of the triple constraints will help with making a management plan for a project.

It will also help the team stay prepared for any changes that might occur during the project progress. The idea is to ensure project success no matter what unexpected obstacles or modifications may arise. 

In other words, the triple project constraints help with pleasing the customer and other project stakeholders by keeping the project team members on budget, on schedule, and making sure everyone stays on point with the project goals.

Whatever project management software you choose, these constraints will be something you have to deal with.

But what are the three primary variables (or triple constraints) in any project?

The 3 constraints of project management

The three project management constraints are connected. Imagine you have the metric of “quality” that is bound on all sides by the relations of each constraint.

The triple constraint includes time, cost, and scope:

1. Time

At the beginning of any project lifecycle you should lay out clearly the overall timeframe of the entire project, including scheduling, deadlines and milestones. Using a Gantt chart is really effective for managing the time constraint. Time management is crucial in its relation to other constraints, as going over deadlines can mean more money and higher budgets.

2. Cost

The next of our project management constraints is the budget or the project cost. Again, this should be done early on during project planning. Making a clear project budget is always related to other constraints, for example, the amount of time your team will require translates to paid wage-labor hours, or a higher budget means you can reach for more lofty goals. 

3. Scope

The project scope is where you explain exactly what are your baseline project requirements. For example, if you are developing a new product, the scope of a project will state what functions it will serve, and how it will be used. 

Good project planning can help prevent scope creep, which is when too many changes get made to the project scope during the project lifecycle without having any contingency plans to readjust the other constraints of time and the cost of the project.

As is clear, any change to one constraint reveals dependencies to the other constraints, that is, one may think of constraint changes as tradeoffs.

A good project manager, with the help of great project management software, will be ready to adapt to changes in real time if the project management constraints are properly envisioned. For this reason, an agile project management methodology works well when considering constraints and their constant relationships in flux. 

Triple constraint example

Let’s imagine some examples of how the triple constraint triangle works in practice.

We’ll see how these constraints impact one another, as sides of the project management triangle that shift the overall shape.

Construction scope changing

Say a client wants to hire a construction firm to build a house with a budget of $1 million dollars, and everything must be completed in 6 months. Then, the client realizes that now they want to add a pool. 

This means the project scope has been changed, and the project manager along with the client must make changes to the other constraints. Which one, or both? 

That is their choice. They can either extend the timeframe of the project to have enough time to build a house and a pool, or increase the budget to hire more laborers to get the whole thing done on time, or both. 

In this case, the scope was increased, so the time and/or the cost must also increase.

Event planning budgeting

Here’s another example. Let’s say you are an event planner, and you get a budget of $25,000 to plan a wedding which will take place in exactly 3 months. 

Then, the client comes into some money and wants to increase the budget for the wedding, but to still have it on the same day. 

You can therefore increase the scope of the wedding, for example, by having a band instead of a DJ, and serve filet mignon instead of chicken. 

Here, the budget increased, so the scope could also increase, while the time remained static.

Website launch scheduling

One final example. You are preparing the launch of a new online store, with a project scope that includes a website, merchandise, advertising, and blog posts for content marketing. Then, your boss wants to move the launch date forward. 

This means that your project schedule has been slashed. You can increase the budget to get more people working on the job or outsource some tasks, or, you can reduce the scope to meet the new deadline on budget, for example, by having fewer items for sale or a simpler website design. 

For this example, you reduce the time, and to compensate, you increase the budget or decrease the scope.


Why are the triple constraints in project management important?

As mentioned earlier, triple constraint project management knowledge is very important for being ready for changes during a project lifecycle. More specifically, changes in costs, timeframe, and/or scope. 

Changes can come from anywhere: the client or stakeholders may request them, or your staff might undergo reshuffling, or various materials and other resources may suddenly no longer be available.

Whether you use an agile methodology like Scrum, or a project management methodology that is more traditional and phase-based, like a waterfall technique or a work breakdown structure, or WBS, having a clear vision of the three interrelated project management constraints is something that project managers and stakeholders simply cannot afford to lose sight of. 


A history of the triple constraint in project management

The exact origins of the theory of the three constraints of a project are shrouded in a bit of mystery. It is possible they emerged from the business wisdom of The Theory of Constraints which came out in 1984. 

The Project Management Body of Knowledge, or PMBOK, also put out a guide to the triple constraint theory, which is reviewed by the Project Management Institute, or PMI. 

According to some literature on the subject put out in 2004, they say the PM triple constraint schema works as “a framework for evaluating competing demands. Project managers often talk of a “triple constraint” – project scope, time and cost – in managing competing project requirements.” 

This quote demonstrates that even in the more recent history of the project constraint theory, there was always a sense of tradeoffs and competing demands. In other words, for optimal quality for the end user, a careful triangular balance must always be marinated when bounded by cost, time and scope.


Current usefulness of project management triple constraint theory

So, some of you might be scratching your heads and saying, is this stuff not obvious? Every project will take time, cost money, and every project has a goal or scope. 

For your team members, how useful is this idea of project management constraints today, really? What is the triple constraint of project management used for in today's world?

While many people realize projects have costs, schedules and promises for what they will deliver, this schema is incredibly useful for reminding people of the relationship between each constraint. For every action, there is a reaction, or there should be lest you fall prey to scope creep, or worse, fail to deliver what the scope of the project promised.

Other more recent criticism of the three project constraints talk about how there are indeed more constraints that need to be included. These include risk and uncertainty, though that is hard to quantify, as well as resources, which some argue are best separated from cost. 

When one gets into program management vs project management, this is particularly the case. Program management entails managing multiple projects, increasing complexity. 

Finally, there is the issue of quality, which is at the heart of project management in general. Some project managers modify the three constraint schema and add quality as a fourth constraint point.


Our conclusion on the project triple constraint model

Nowadays, there are many excellent project management tools that help you envision and plan around the triple constraints. Many of these apps have templates already set up where you can plug in your data for costs and budget and scope.

Well, hopefully you have learned everything you needed to know about project management constraints, what the 3 project constraints are, and the theory highlighting the relationships between them. 

Ultimately, no project should lock you into any one shape or frame of mind. It’s all just metaphors. But when it comes to being ready for anything during a project lifecycle, knowing your bounds of time, money and scope will help you out of any serious project jam.