Plan-Do-Check-Act (PDCA) Cycle

ISO Management System standards such as ISO 9001 (Quality) and ISO 14001 (Environment) are based on the methodology known as Plan-Do-Check-Act (PDCA).

The PDCA methodology was originally developed as a process for making changes and problem solving. Organisations that implement a management system that complies with the requirements of the ISO 9001 (Quality) Standard will manage their operations via the application of a system of processes and their interactions, which is referred to as the process approach.

The PDCA and Process Approaches are compatible as PDCA can be applied to all processes.



The four phases in the original Plan-Do-Check-Act Cycle involve:

Plan: Identifying and analyzing the problem.

Do: Developing and testing a potential solution.

Check: Measuring how effective the test solution was, and analyzing whether it could be improved in any way.

Act: Implementing the improved solution fully.

These are shown in Figure 1 below.


There can be any number of iterations of the “Do” and “Check” phases, as the solution is refined, retested, re-refined and retested again.



The four phases in the modified PDCA Cycle used in the ISO 9001 Management System Standard involve:

Plan: establish the objectives and processes necessary to deliver results in accordance with the organisation’s policy.

Do: implement the processes.

Check: monitor and measure processes against the policy, objectives, targets, legal and other requirements, and report the results.

Act: take action to continually improve performance of the management system.

The modified PDCA Cycle is shown below:

  ISO 9001 PDCA


As with any organisational improvement tools the PDCA Cycle is only useful if it is implemented and incorporated into existing processes. The Plan-Do-Check-Act (PDCA) Cycle provides a simple but effective approach for problem solving and managing change, ensuring that ideas are appropriately tested before committing to full implementation. It can be used in all sorts of environments from new product development through to marketing.