How to Complete the Six Sigma SIPOC Diagram

This Article is the first in a four part series to show you “How to Complete a Six Sigma Root Cause Analysis”. The series covers four tools:

Supplier, Input, Process, Output, Customer Requirement.

The SIPOCR is an Acronym for Supplier Input Process Output Customer Requirement. The SIPOC Diagram is one of the Most Important tools in a Lean and/or Six Sigma project. This tool will help the team identify whether they have focused on the right process. The SIPOCR will also help the team to understand who their Customers are and what are their Requirements.

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The SIPOCR helps us break down our process into External Inputs and their Suppliers; Process Steps; and Outputs, Customers and their Requirements. This diagram allows us to see the process from the 30,000 foot view.

The Picture below is a basic diagram to understand the SIPOCR:


SIPOCR Example:

I like to use the example of Mowing a Lawn to describe the Diagram above. The Scope of “The Process” is inside of the box. The “External Inputs” (left of the box) are those things that have to be fed to the process in order for the process to work.

Let’s say that the Scope of The Process of Mowing the Lawn starts with: You are standing behind the lawnmower, it is running and ready to mow the lawn. What has to be fed to The Process in order for the Process to Work?

  • Someone (or Something) to push the lawnmower
  • A Lawnmower
  • Knowledge of how to work the lawnmower
  • Proper Weather

Why is it important to understand our Internal Inputs? Our focus during the Lean and Six Sigma Project will be on the “P” in the SIPOCR. What if we are focused on the wrong process? By understanding our “External Inputs”, we might find one or more “External Inputs” have a significant effect on our “Process Output”.

By not addressing that Input, we may not make a significant enough improvement to our “Process Output”. One of the Most Powerful aspects of a SIPOCR is to help a project team determine if they have the right focus.


    Below is an example of a completed SIPOC using a simulated project that we give to our Lean Six Sigma Green Belts and Black Belts as a benchmark to complete their Lean Six Sigma project. The project is focused on a company called PBJ, Inc. who makes thousands of Peanut Butter and Jelly sandwiches for kids in schools all over the continental United States. PBJ Inc is experiencing increased operating costs in the construction of PBJs and they do not know why. The SIPOC below is part of a project to determine the root cause. 
    The first half of the SIPOC:

The 2nd half of the SIPOC:


Step #1a: Fill out the “Process Name”

  • State the process in which you believe the problem occurs
  • In this example: “PBJ Process” is the Process Name (we believe that the increase in operating costs is occurring because of variation in the construction of peanut butter and jelly sandwiches)

Step #1b: Fill out the High Level steps in the Process.

  • Use verbs or adjectives – how does the process operate from the 30 thousand foot view
  • These are not detailed steps (We will get to the detailed steps later in a tool called the Input Map)
  • There should be no more than 10 high level steps
  • If you have more than 10 steps, your project may be too large in scope

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This FREE Downloadable ZIP file contains seven templates in the Lean Six Sigma Root Cause Analysis toolset (Including the SIPOC). Each template is in a Microsoft Excel format. These tools are used in the DMAIC (Define, Measure, Improve, and Control) phases of a Lean Six Sigma Root Cause Analysis.

Step #2: Fill out the “Outputs” section.

  • Should have no less than three Outputs (this is important in a later Six Sigma Root Cause Analysis Tool).
  • Use nouns – what does this process produce?
  • Output should not contain verbs (action words) nor requirements (we will list requirements in another column)
  • Outputs should not be written in the Positive (like “Good Taste”) or Negative (like “Bad Taste”) only in the Neutral (like “Taste”)

Step #3: What are the Requirements of the Outputs?

  • The requirements are given in metrics or references to where the metrics exist

(Optional) Who are the “Customers”?

  • Who receives the Output
  • Who will benefit from this process?
  • Who will be upset if this process doesn’t work as required?
  • Can be both Internal Customers and/or External Customers

Step #4: What are the External Inputs to the Process”?

  • The External Inputs are those Inputs that supplied to the process in order for the process to function
  • These External Inputs are outside of the scope of our LEAN or Lean Six Sigma project
  • These “External Inputs” are external to the “Process” that our Six Sigma Project is Focused.
SIPOC-External Inputs
SIPOC-External Inputs-Color Key

Once the External Inputs have been identified, we then color code them based on the effect they are presently having on the Outputs.

The External Input column is important in verifying that our focus is in the right place (the Process or the “P” in the SIPOC). We might find from the External Input column that we need to re-focus up stream to one or more External Inputs to truly solve the problem.

(Optional) Who Supplies the Inputs?

  • Who supplies the External Inputs to the Process?
  • You don’t need to list every specific supplier unless the specific supplier detail is important to the variation in the output.
  • For Example, If the variation in taste is impacted by the different suppliers of Peanut Butter, then we would list the suppliers in that level of detail.

Once the SIPOCR is completed, and the Scope (or Focus) of the Process that is to be Investigated has been verified, then you can move to the next step. The next step in the Six Sigma Root Cause Analysis is the Input (or Variables) Map.


The SIPOC is one of the most powerful tools in the Lean Six Sigma toolbox. It helps the process improvement team and the stakeholders understand the project scope and requirement. The SIPOC also helps the team understand if they are focused on the right process.

How could the SIPOC help you in your project?