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The project triangle

Finding the balance between scope, costs and time

The project triangle

Whether a project can be completed successfully or not depends on many different factors. However, the three factors of cost, time and scope are particularly important. The interrelationships between these factors and the resulting conflicts of objectives are illustrated by the project triangle.

What is the project triangle?

In classic project management, the three dimensions of scope, time and cost are defined and project control is then based on them. By creating the project triangle between these three dimensions, it is possible to see how they are interlinked and therefore also the need to harmonise these three dimensions in order to complete a project successfully. This shows that a change in one of the variables will simultaneously result in changes in the other two dimensions in order for the triangle to hold together. Thus, a project manager has the task of balancing all three dimensions so that the project meets its budget and schedule, as well as fulfils all specifications of scope. This task can be difficult because the three dimensions usually compete with each other.

The project triangle

The three dimensions

In order to optimally balance the three dimensions of the projec triangle, a project leader should have a great understanding of how they can be influenced and where opportunities exist to adapt to changes in the course of a project. Therefore, it must be clear what they are composed of.

1. Costs

This dimension includes not only the pure budget of a project, but also the available resources. This is because resources can be traced back to a financial value. For example, if additional staff is to support the project, if new equipment or additional rooms are needed, all of this will cause higher costs. Therefore, this point includes, among other things:

  • The budget, i.e. the financial framework of the project
  • The number of team members
  • Available equipment and devices
  • Available office space

2. Time

The dimension of time also goes beyond the mere duration of the project. Included are, among others:

  • The project timetable as well as the number of project phases
  • Hours worked on the project
  • Time spent on planning and strategy
  • Internal calendars and targets

3. Scope

The scope of a project includes both the scope of the project outcomes and their quality. In traditional project management, it is determined before the time frame as well as the budget. These include:

  • Scope of work
  • Level of detail of the final product, e.g. number and complexity of functions
  • Quality of the results
  • Quantity of end products or number of product developments

Our tip: In classically managed projects, scope creep can occur in the course of a project, i.e. an expansion of the scope of work without a simultaneous adjustment of budget and time. Therefore, it is important that the planned scope of services and its quality are documented and signed off before the project begins. Each change should also be documented as well as its impact analysed and appropriate adjustments should then be made in budget and time planning. In this way, the changes can be approved, also in terms of budget and time.

How the three dimensions relate to each other

There are two different types of relationships in the project triangle. On the one hand, the relationship between the scope to be achieved and the other two variables is directly proportional. This means that scope moves in the same direction as time and cost. So if the scope of a project increases, for example because the volume is increased or the quality is improved, the available time and / or the costs must also be adjusted.
The relationship between costs and time, on the other hand, is inversely proportional, with the variables moving in opposite directions. Thus, if costs are to be reduced, time must be increased. If a project is to be completed more quickly, so the time dimension is reduced, the costs must increase.
This leads to the following insights:

Finding the balance in the project triangle

How the magic triangle helps in project management

It is very unlikely that there will be no changes in any of the dimensions of the project triangle during the implementation of a project. Therefore, the central idea behind the concept is that a project cannot be successful if all three dimensions are rigidly fixed. So, in order to have some leeway for any necessary adjustments, at least one of the dimensions should be flexible. Therefore, you should choose your focus carefully and coordinate it with the stakeholders of your project. In this way, the project triangle helps you with project planning and control, with controlling, but also with risk and change management. If your focus is on keeping to the schedule, it is advisable, for example, to have an additional budget approved before the start of the project for any additional resources that may be required, or to clarify which deliverables are optional. If, on the other hand, your focus is on keeping to the budget, you should clearly communicate that the end date of the project will have to be postponed or the scope of deliverables reduced if there are unforeseen changes.

Our tip: To ensure clarity before the project starts and to know exactly how to proceed in case of changes, you should already document the most important points in the project order or project manual. This includes:

  • The client’s preferences in case adjustments need to be made.
  • Any pre-approved contingency budget
  • A list of the most likely changes, as well as possible action plans for them, describing the impact on time, cost and scope.

During project implementation, keep all three dimensions in mind at all times so that you can react to changes at any time or think of measures to take if a change occurs.

Differences in traditional and agile project management

In traditional project management, it is assumed that the scope is fixed, as it is defined in terms of scope and quality, for example in the specifications. Costs and time are more flexible in this case. They are planned, but can change if necessary.
Agile project management, however, turns this view around, so that costs and time are fixed, but scope can be adjusted. This is because the iterative planning in Scrum, for example, uses so-called sprints in which the work is done. Their number or duration is usually fixed, which also makes the costs of a project easy to estimate. Thus, it is the scope that is variable.

Extensions of the project triangle

Today, it is often no longer sufficient to focus on just three dimensions in project management. Therefore, the dimension of scope is often subdivided into quality and content. One then speaks of the magic square or the devil’s square.
In addition, the project triangle can be extended to include the all-encompassing factor of customer satisfaction, which is about the satisfaction of all stakeholders. Since they usually have different demands on a project, it is important that the needs of all project stakeholders are addressed.


The project triangle is well suited for visualising the interrelationships of the most important factors in project management: time, costs and scope. It quickly becomes clear that these dimensions should be balanced and that a change in one dimension will result in a change in the other dimensions. A realistic assessment of all three factors at the beginning of the project as well as setting the right priorities and clear communication are therefore of high importance for the success of a project.
With project management software such as myPARM, you can keep an eye on all three dimensions at all times and thus take action if something changes in one dimension. Real-time reporting in dashboards with all the important key figures and an early warning system help you to do this. If changes occur in one of the dimensions, you can quickly see within the software how these changes affect the other factors and therefore how you can intervene.

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