Triple constraint triangle or project management triangle is a constraint model where scope, schedule and cost are constraints forming the sides of a triangle, with quality as the central theme.

In project management, the Triple Constraint Triangle, also known as the Project Management Triangle or Iron Triangle, represents the three primary factors that must be balanced to ensure successful project completion. These factors are:

Scope: This refers to the work that needs to be accomplished to deliver a project’s intended outcome. It includes all the tasks, features, deliverables, and objectives that must be completed within the project timeline.
Time: Time represents the project’s schedule or the duration required to complete the project. It includes deadlines, milestones, and any time-sensitive aspects of the project.
Cost: Cost refers to the financial resources needed to complete the project. This includes expenses such as labor, materials, equipment, overhead, and any other associated costs.

The Triple Constraint Triangle illustrates the interdependency of these three factors. Any change in one factor will inevitably affect one or both of the other factors. For example:

Increasing the scope of a project without adjusting time or cost will likely lead to delays and increased expenses.
Attempting to accelerate a project’s schedule may require additional resources, thus increasing costs.
Cutting costs without adjusting scope or schedule may result in reduced quality or incomplete deliverables.

In essence, project managers must carefully manage the balance between scope, time, and cost to achieve project success. This often involves making trade-offs and decisions based on project priorities, stakeholder expectations, and available resources.