The Iron Triangle of Project Management

Balancing Your Budget, Scope and Schedule

(Also Known as The Triple Constraints of Project Management)

The Iron Triangle of Project Management - Balancing Your Budget, Scope and Schedule

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Find a balance between the three points of the "iron triangle" for project success.

Imagine that you're managing the rollout of a new brand logo for your organization. At first, everything's going great. But, after a few weeks, some issues start to crop up that take you down a different path.

First, you realize that you've forgotten to factor in some costs in the printing and manufacturing process. Then, a few other tasks take longer to complete than you predicted.

You could recruit some additional contractors to get the rollout done on time. But, that will mean reducing the budget elsewhere. You consider not spending the extra amount on printing and manufacturing, but this might mean that you have to reduce the scope of your project, or push back the launch date.

This example demonstrates just how closely budget, scope and schedule are linked when you manage a project, and how small changes in one area can affect the other two.

In this article, we'll examine the relationship between these three common constraints, and explore some strategies for overcoming them.

What Is the Iron Triangle of Project Management?

The Iron Triangle refers to the three key constraints that can affect a project. These are budget, scope and schedule (see figure 1).

They form what is known as the "iron triangle" because you can rarely change one without impacting the others or damaging the quality of the overall project.

These three parameters are usually established in the mandate and charter documents, written at the start of the project to define its objectives.

Figure 1 – The Iron Triangle of Project Management

The Iron Triangle of Project Management - Diagram

Original diagram in the article, "What is Project Management?" Reproduced with permission of the Association for Project Management.

Throughout the project, the decisions that you make regarding these three constraints can impact the quality of its objectives, positively or negatively.

For example, suppose that your project mandate is to launch a new standalone IT system, but you have an unexpected issue to resolve – the design phase has overrun. You now need to consider which of the three constraints to change or "trade" to ensure that the project is successful. You have three options:

  1. Extend the schedule: the new system will be launched later than planned, which may not be an acceptable solution to your stakeholders. It will also likely increase your labor costs. However, there may not be any negative impact on the quality of the end product.
  2. Re-plan the rest of the project so that it's still delivered on time: this might increase the risk of failure, particularly if you forego or reduce stages such as testing or training. This, in turn, may impact the quality of the project objectives, and may result in increased costs.
  3. Change the scope: you could remove some of the elements of the original project scope (for example, functionality, systems, interfaces, automated processes, or departments supported), so that it can still be delivered on time and on budget. However, this may mean that you forfeit some of the project's original goals. Overall costs may also increase if you opt to deliver these objectives at a later date.


In project management, there's a saying that goes, "Speed, cost, quality. You can't have all three, so choose only two." This means that:

  • If you deliver the project quickly and cheaply, then it probably won't be very good.
  • If you deliver it quickly and to a high standard, then it won't be cheap.
  • If you deliver it to a high standard but cheaply, you won't get it very quickly.

Although not every project will follow one of these three scenarios, there is some truth in the saying. So, when difficult issues arise, be sure to think carefully about the solution, and to consider its impact on other areas of your project.

How to Use the Iron Triangle in Decision Making

When problems, changes or risks crop up during your project, a good starting point is to assess them against the iron triangle. Use the questions below to guide your decision making:

Problems With the Schedule

  • Review your critical path (these are the tasks that must be completed for the project to be successful). Are all of the tasks essential to deliver the project objectives? Are any unnecessary? Can you remove some?
  • Can you re-plan and do tasks differently, or in a different sequence, to reduce your overall timeline? Can you carry out some tasks simultaneously to reduce the time required?
  • Is contingency time built into the later phases of the project? Can you use this time now, or would this only delay the problem?
  • Could you move some of the scope components to a future project phase, so that you can deliver the current phase on time?

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Problems With the Scope

  • Is the proposed change to the scope essential for delivering your key objectives for this phase? Would it be more appropriate to add a new scope request to a "wish list" to consider later?
  • Can you move some areas of the scope into a later phase?
  • Is the definition of what you want to achieve clear enough for the project to continue? Do you need to suspend the project and review the business requirements before proceeding further?

Before you make a decision, remember that even minor changes to a project's scope can have an impact. Allowing too many small changes, without thinking carefully about the implications, can lead to the project growing beyond its initial boundary.

If you suspect that this kind of "scope creep" is occurring, conduct a project review to look at the project as a whole. Then decide how best to take things forward. For instance, could you split the project in two, create a new phase, or extend the deadline?


To reduce the likelihood of changes being made to the scope during the project, get stakeholder involvement and approval of the business requirements and design phases as early as possible.

This will ensure that your project objectives are complete before going ahead. Also, make sure that you have a scope control process in place, so that you don't make promises to stakeholders that you can't keep.

Problems With the Budget

  • Can you deliver any tasks more cheaply? Could you use cheaper components or cheaper resources, without negatively affecting the quality of the finished product or service?
  • Do all of your planned tasks contribute to the project's outcome? Can you remove any?
  • Can you reduce the project team's expenses? For example, could you reduce travel costs by allowing remote working?
  • Do you have any cheaper contingencies that you can use?

Making a Final Decision

Before you make any major changes to the project's schedule, scope or budget, remember to consider the bigger picture.

Fore example, don't forget the key objectives that you need to deliver, and when you need to deliver them by. Also, make sure that the project will still provide the majority of the benefits that you originally set out.

You'll also need to ensure that you keep your stakeholders "in the loop" throughout. Project sponsors and steering group members, in particular, can also help to guide your decisions, as they often have the advantage of being able to look at the project from an outsider's perspective.

Before you make a final decision, discuss which high-level options would be appropriate, and establish what flexibility you have in your budget, delivery times, scope, and quality requirements. This will make it easier to communicate any serious issues, major risks, and changes to the scope.

Key Points

The "iron triangle" of project management refers to the three main constraints that can affect the success of a project. These are:

  1. The budget.
  2. The scope.
  3. The schedule.

They are known as the iron triangle because a change to one often impacts the other two. For example, if a project's scope is extended, it will likely require an increase in budget and will mean that the deadline needs to be moved forward.

The challenge of project management is to balance the three points of the iron triangle, without affecting the overall quality of the finished product or service. To do this, you may need to ask questions and make tough choices, so that the project still delivers what was promised.

Before making any changes, however, remember to consider your original objectives. Get support from your stakeholders, and keep them informed of your progress. Finally, make sure that you have the flexibility to make the changes you want before doing so.