Lean vs Six Sigma

The manufacturing industry often relies on either Lean Manufacturing methodologies or Six Sigma. Both Lean and Six Sigma are the obvious choices of what they offer to manufacturing facilities and end-users. The debate on the methods to eliminate defects is quite prolonged. But the truth is both Lean, and Six Sigma offer groundbreaking approaches to address wastage during production.

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Both tools are great options for eliminating waste while improving cyclo efficiency and process flow. For all manufacturing organizations in the world, flow improvements are a great deal. Lean encourages general and daily improvements, whereas Six Sigma is data-based and targets specific improvements for each project. Lean vs Six Sigma, there are notable distinctions, both theoretically and practically. It is important to understand the difference that sets both methodologies apart from each other.

Irrespective of their subtle and noticeable differences, Lean and Six Sigma have similar goals. Both focus on eliminating production waste by creating an effective system. The guide will provide readers with a comprehensive guide on Lean, and Six Sigma key differences as their approaches make them different.

Lean vs Six Sigma - Difference between Lean and Six Sigma 

So, let us begin with the Lean definition first, which I am going to talk about in the section below.

What is Lean?

Toyota came up with Lean to improve the overall process of manufacturing. Lean addresses waste removal strategies and methodologies that aid manufacturing facilities across the world. With Lean, any activity which doesn’t seem to add value to end-users and the organization should be eliminated.

Lean focuses on eight major areas to eliminate waste and make production fruitful:

  • Overproduction
  • Underlying defects in any processes
  • Idea or Waiting that differentiates operations
  • Not utilizing the raw talent of employees who can bring skill to the table
  • Overabundance inventory
  • Wasteful process for transportation
  • More processing than required which doesn’t add value to the production
  • Unnecessary actions which machine and employees tend to make

Lean came into being with a single-most goal to make manufacturing a treat for production facilities. Hence, Lean can be implemented on a varied niche of industries and all different operation types. Lean never focus on a single point, instead to optimize, Lean incorporates numerous technologies, departments, and assets even before the production reaches end-users.

As lean emphasizes the whole flow process rather than concentration on isolated points, the methodology goes beyond eliminating waste. Instead, it creates a continuous improvement culture across organizations.

Taiichi Ohno, a notable Toyota executive, was the first to identify seven types of waste (Muda). Upon identification, the revolutionary Toyota Production System came into being. Further, Lean did encompass several processes of improvement over the years, like World Class Manufacturing. As per the very essence of Toyota Production System, Lean seeks to shorten the lead times, minimize waste and at the same time enhance efficiency.

Related Article: What is Lean Management?

Lean Benefits

  • Reducing lead time
  • Increasing throughput
  • Eliminating Waste
  • Providing values to customers
  • Curating massive profitability
  • Enhancing overall delivery time

Lean Methodology Roadmap

Lean Methodology Roadmap

Lean shares an uncanny similarity with Six Sigma as it uses DMAIC, meaning Define, Measure, Analyze, Improve, Control. Irrespective of the similarities, Lean is entirely different from Six Sigma as it utilizes a step-by-step methodology to solve chronic problems. The roadmap of Lean DMAIC are as follows:

It defines value:
  • Lean Define the importance of CTQs and stakeholder
  • Define the customer's increasing demands
  • Maps resource-consuming process
  • By providing assesses to implement 6S

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Measures Value:
  • The demand of the customers
  • Curate plans to collect data
  • Validates measurement system
  • Determine takt time, pace, and lastly, workforce
  • Creates mapping for value stream
  • Identifies the capacity constraints and replenishment
  • Implements S1-S3 from 6S
Analyze the flow of the process:
  • By analyzing the value stream map
  • Explores load and process capacity
  • Performs VA/NVA decomposition analysis
  • Solves special causes by utilizing Lean holistically
Related Article: Lean Manufacturing Tools
Enhance process pull

 Runs everlasting improvement events

  • Designs both process flow and changes
  • Balances, loads, and feeds the process
  • Standardizes most work tasks
  • Implements never-seen-before processes
Controls Process
  • Refines and stabilizes value stream
  • Completes visual and process controls
  • Identifies opportunities concerning mistake-proofing
  • Implement S4-S6 from 6S
  • Oversees results to close up projects
Related Article: Lean Interview Questions for Beginners

What is Six Sigma?

Back in the early 80s, Bill Smith at Motorola came up with the Six Sigma concept for improving the quality of products by measuring defects. Over the years, Six Sigma is spread across different verticals and industries. Six Sigma universally stands for the continual process of improvement.

It focuses on reducing errors and variance in both conventional and modern-day production processes. As Six Sigma reduces friction, it ultimately leads to producing top-notch products and services. If manufacturing units don't pull off dependability, it leads to unforeseeable errors and defective products. Six Sigma's usual standard is to reduce the defect to approximately 3.4 per million opportunities.

Moreover, Six Sigma offers distinctive belt classifications like a green belt, master black belt, yellow belt, and black belt. Employees often have to learn the methodology of different straps and the in-depth knowledge that comes with the platform.

Related Article: What is the Six Sigma Green Belt?

Six Sigma comprises two essential methods: fact-based and data-driven to identify and eliminate the overall process. Two methods of Six Sigma are as follows:

  1. DMAIC (Define, Measure, Analyze, Improve, Control) - The methods help correct the persisting issues in processes. 
  2. DMADV (Define, Measure, Analyze, Design, Verify) - The process helps create brand new processes if there's a need.

Six Sigma is all about improving critical CTQs, which is denoted as T.

Further, this makes the equation "Y + f(x)" that guides the team by communicating the project which should be accomplished.

When the whole of Ys is understood, it becomes essential to measure them and determine the target's meeting. Analyzing Ys is necessary to understand the characteristics' processes which ultimately leads to variation. Lastly, the interpretation will be reduced to control variables. The variables here are regarded as "Xs."

During a production process, there could be several Xs that could impact the stand of Y. However, if Y becomes the function of X, then it would be essential to define the overall Xs with absolute precision to have authority over them ultimately.

Y = f (x1, x2, x3, x4,…)

Related Article: Interview Questions on Six Sigma 

Lean vs Six Sigma Differences

Lean isn't the perfect or close to an ideal replacement for Six Sigma & vice versa as both methods are very different approaches. The quest or the endeavor they share, like achieving efficiency, effectiveness, and cost reduction, has already made the world a better place. Moreover, both Lean and Six Sigma focus on entirely different problems. As a business owner or a consumer, it is essential to note the differences theoretically and practically.

Lean vs Six Sigma #1: Difference in History and Goals

The present-day Lean & Six Sigma practices have seen a lot of evolution throughout the years. Moreover, both of the manufacturing methodologies were born to address complex environments for manufacturing. At first, Lean became mainstream for automotive brands in Japan. However, when the western counterparts began integrating Lean into their businesses, distinctive versions of Lean came into being.

Six Sigma and Lean have similar goals to eliminate waste and increase systems' efficiency. However, as the definition to address the waste differs in both cases, their stance makes them poles apart.

Lean vs Six Sigma #2: Defining Waste

Theoretically, the most significant difference between Six Sigma and Lean is how practitioners identify wastes. In terms of Lean, waste refers to an activity or process that doesn't substantially value customers. On the other hand, in Six Sigma, waste reduction focuses on one task at a time.

Lean practitioners also focus on optimizing any processes that have the potential to create value. Six Sigma's ultimate goal is to eliminate defects by simply reducing variability.

Lean vs Six Sigma #3: Practice and Mindset

Another notable difference between Six Sigma and Lean lies in its mindset. When manufacturers implement Lean comprehensively, it will enable aiding people to make intelligent decisions. Lean idealists tend to apply continuous improvement methods to figure out ways to eliminate wasters and increasing value.

It is easier for anyone to become a Lean thinker to apply consistent improvement methods to make production efficient.

Six Sigma is a completely structured, systematic program that tackles organizations' platforms by reducing risk and vulnerability. Six Sigma is famous for its certification system. In an organization, individuals with any experience can operate Six Sigma. The basic rundown of the platform are:

  • Black Belt: It trains, coaches, and aids in leading problem-solving projects.
  • Green Belt: Aids in analysis and collecting data for the Black Belt projects.
  • Master Black Belt: It helps to coach or train both Green and Black Belts level professionals. Master Belts also functions at the Six Sigma program level by simply curating strategic direction and critical metrics. An organization that uses Six Sigma, Master Black Belt, acts as an internal consultant and a technologist.
  • Yellow Belt: Team members come together to participate in the completion of a project. Yellow Belts help in reviewing process improvements which completely supports any project.
  • White Belt: An excellent addition for local teams to solve everyday problems concerning projects. Even if the team isn't a part of the Six Sigma project, local groups can still overcome any issues.

Lean vs Six Sigma #4: Functional Areas

Today, Lean Practices are an integral part of software development, where Lean still has a hold. Organizations and team parts of the said organizations rely on the fundamental principles of Lean to bring more value to their customers.

Six Sigma is curated to work even in complex environments by diminishing variability and reducing risk to attain a breakthrough. Six Sigma is perfect for application in a wide array of functional areas like manufacturing, engineering, sales/marketing, plant operations, and customer service. Six Sigma requires a lot of resources to run efficiently.

Lean vs Six Sigma #5: Leadership

Six Sigma provides numerous certifications which are hierarchical, structured for leadership. Additionally, Six Sigma is a perfect addition to perfectly compartmentalized organizations. Six Sigma's certification programs empower professionals to perform specific roles by localizing problem-solving skills, training teams for projects, and helping individuals lead during complex instances.

On the other hand, Lean provides fluidity by encouraging practitioners to have big goals in solving organizational problems irrespective of whether the individual is an executive or contributor. Lean is very well suited for properly structured environments; however, it is best for an autonomous organization, enabling open collaborations across different management levels and departments.


Transformations businesses and organizations either implement Six Sigma or Lean for ensuring optimum manufacturing. Even if there are notable differences between Lean and Six Sigma, both platforms streamline production and eliminate waste. Irrespective of whether organizations need continuous, lightweight improvement, both Six Sigma and Lean are more than capable of fulfilling production needs. Organizations can also choose to go with the best virtues or Lean and Six Sigma if they have the resource. The ultimate goal is to accumulate and analyze data to make vital decisions in the long run.

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Last updated: 03 Apr 2023
About Author

As a content writer and storyteller, Raunaak Mitra regards himself to be a prodigy in writing. He firmly believes that language is borderless, and anyone can write as long as they have a strong narrative capability and the ability to emote feelings into words. Authors like F. Scott Fitzgerald and R. K. Narayan have influenced him to keep the writing as simple as possible for anyone to understand. Other than being well-versed about technological trends like AI, Machine Learning, AR, VR, Gaming, Microprocessors, Cloud Computing, Industry 4.0, literally any technological advancement (old or new), he also shares a knack to curate fiction on sci-fi, satire, and thriller genres.

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