A constraint is something that imposes boundaries on your project activity [tensix, 2019]. The triple constraints of project management are time, cost and scope. Not surprisingly these areas are Scope (the what and how?), Time (the when?) and Cost (the how much?). The Triple Constraint, also known as the Project Management Triangle, or the Iron Triangle.  It is the relationship between the three most important restrictions in a project.​

Time is a project constraint because often projects have fixed deadlines or milestones that must be achieved at a certain time, which determines below steps,​

  • Work Breakdown Structure (WBS)​
  • Task dependencies​
  • Network Diagram​
  • Gantt Chart​
  • Resource leveling​
  • To control project earned value analysis is necessary which shall be discussed in EVM posts.​

When it come to cost; Analogous Estimating and Parametric Estimating comes to consideration, where Top Down Estimating and Bottom Up Estimating methods are used based on project.​

Coming back to triple constraint, even a very superficial knowledge of geometry will reveal that you cannot change one without it having an effect on the others. i.e, if you increase the scope (make the scope side longer) and you want to still deliver at the original duration, you have to accept that the cost will probably increase. It's therefore critical that we control all constrains in a balanced way, because they do not exist in isolation.​

In time of knowledge evolution, the triple constraint has been focused more from Cost, Time and Quality to clear that Scope in a way covers the product quality aspect and the achievement of the delivery of project scope within time and budget probably guarantees the quality of project management.​


  • Smartsheet. 2019. The Triple Constraint Theory of Projects | Smartsheet . [ONLINE] Available at: https://www.smartsheet.com/triple-constraint-triangle-theory.​
  • The Digital Project Manager. 2019. What Is And How To Manage The Project Management Triple Constraint - [ONLINE] Available at: https://thedigitalprojectmanager.com/triple-constraint/.​
  • Ten Six Consulting. 2019. What is the Project Management Triple Constraint?. [ONLINE] Available at: https://tensix.com/2019/02/what-is-the-project-management-triple-constraint/.​
  • ProjectEngineer. 2019. The Triple Constraint. [ONLINE] Available at: https://www.projectengineer.net/the-triple-constraint/​