Triple Constraints of Project Management: How the Iron Triangle Works

If you’ve ever managed a project, you know it can be next to impossible to deliver all the bells and whistles a client wants on a tight timeline and a shoestring budget. Something’s gotta give.

This all-too-common deliverable dance is a great example of why it’s important to know how to manage project constraints effectively.

The triple constraint theory is a simple method you can use to keep project expectations in check. Let’s start with a definition.

What is triple constraint?

Triple constraint is a project management concept that says every project operates within the boundaries of scope, time, and cost. A change in one factor will inevitably affect the other two.

As a project manager, it’s your job to balance these 3 constraints and manage expectations so everyone understands what it takes to achieve project success. In other words, it’s all about trade-offs.

For example, if a client wants to add a bunch of new features to the project’s scope, they’ll have to budget more time and money to get the project done. Or if your boss slashes your project budget, you’ll need to scale back the requirements.

What is the iron triangle of project management?

The “iron triangle”—sometimes also called the “project management triangle”—is a visual representation of the triple constraint model. Each side or point of the iron triangle represents one of the 3 constraints of project management:

• Time: What’s the deadline for project delivery?
• Cost: What budget does the project need to work within? 
• Scope: What requirements and/or deliverables are included in the project?

How to manage the 3 constraints of the project triangle

Triple constraint theory is all well and good. But how do you put this project management framework into practice?

It’s all about keeping your eye on the ball.

Let’s dig a little deeper into ways you can effectively manage each project constraint, using TeamGantt as an example.

1. Managing scope constraints

Scope creep has a funny way of sneaking up on you. Before you know it, “just one more thing” has turned into a completely different project deliverable.

That’s why it’s important to define goals and document project requirements before work begins. That way everyone knows what “done” looks like, and you have a project truth to refer back to if the scope starts to creep.

Adding more features can stretch a project’s time and budget constraints. You’ll either need to extend the deadline or assign more people to the work, increasing project costs. Monitoring scope changes enables you to discuss trade-offs early and make necessary adjustments before your project gets off course.

TeamGantt tip: Communicate scope to your team

Keeping the nitty-gritty scope details all to yourself doesn’t do anyone any favors. Using TeamGantt’s sticky note feature to outline scope requirements on the task or project level not only ensures your team has crystal-clear direction. It also empowers them to raise a flag if they see the scope start to creep.

2. Managing time and schedule constraints

In project management, most folks know, if you want a project done fast, it’s gonna cost you—especially if you’re not willing to bend on the scope. That’s because a short deadline requires more resources to get the work done on time.

A detailed scope document provides the perfect foundation for understanding your project’s time constraint because you can use it to build out a project estimate. Be sure to bring your team into the discussion and look beyond task hours. The time you spend in meetings or holding a stakeholder’s hand through the process counts too.

The more accurate your estimate, the better. After all, it’s what you’ll use to schedule work and drive project decisions if tough choices need to be made to meet the project deadline.

TeamGantt tip: Set and track deadlines

A gantt chart makes it easy to build and monitor your timeline to ensure your project finishes on schedule. Add milestones to highlight important dates and deliverables, and use baselines to compare your planned vs. actual timeline as your project progresses.

Want a quick snapshot of project delays? TeamGantt’s Project Health Report shows you which tasks are falling behind and which ones are already overdue. If timelines shift, rearrange deadlines in an instant with drag and drop scheduling.

3. Managing cost and budget constraints

Estimating a project’s time and effort also forms the basis for your project budget. Here are a few costs to consider when formulating a project budget:

• Resource costs, based on estimated hours (or story points in Agile project management)
• Materials
• Equipment

When it comes to budget constraints, remember, it’s best to communicate early and often. No one likes being surprised by a big bill (or the tense conversation that inevitably follows).

If an unexpected expense pops up, take time to explain how it will impact the rest of your project, and let your client decide whether or not it’s worth the extra dough. Your client isn’t a project expert and may not realize how much that shiny new feature will cost them in the end.

TeamGantt tip: Monitor resource costs

Time is money in any project. Paying attention to how the time spent stacks up against your estimate helps you keep project costs in check.

TeamGantt’s hourly estimation and time tracking tools enable you to compare a task’s actual vs. estimated hours and see how the time spent tracks against the percentage complete. That way you can spot budget overages before they become a problem.

It’s also easy to schedule and track all your resources directly from your project timeline so you don’t accidentally overbook people or pay for equipment that isn’t actively being used.

Further reading: How to Manage Project Resources with a Gantt Chart

Examples of other project constraint frameworks

Triple constraint may be the most common approach to managing project constraints, but it isn’t the only model.

Quadruple constraints of project management

Some project managers also take quality into account, placing it either at the center of the iron triangle or as an additional point that forms a 4-point diamond. Here’s an example of the quadruple constraints of project management:

6-constraint project management star

Still others take a 6-constraint approach to project management. This framework adds process factors like quality, resources, and risk as a second triangle atop the standard triple-constraint model. The result is a star-shaped visualization of project constraints.

Of course, the more constraints you factor into a project, the more complicated it gets to balance them all. While these additional constraints are worth consideration in any project, focusing on scope, time, and cost as your primary variables can help keep things manageable.

Get easy visibility for managing project constraints

If you want to win at project management, you’ve got to be a pro at wrangling scope, time, and cost. With TeamGantt, it’s easy to balance project constraints so everyone’s happy with the outcome.

You’ll have all the features you need to ensure projects finish on time and under budget, including:

• Drag and drop scheduling
• Easy team collaboration
• Multiple workflows and project views
• Flexible resource management
• Planned vs. actual timeline
• Hourly estimation and time tracking

Best of all, it’s all wrapped up in a simple and intuitive interface anyone can navigate.

Give TeamGantt a free try today!