Six Sigma vs Lean Six Sigma: Difference Between Six Sigma and Lean Six Sigma

Lean and Six Sigma are two of the most popular process improvement methodologies used in business today. With origins in manufacturing, both focus on reducing waste and defects, albeit with different approaches.

Lean aims to optimize workflow and maximize value, while Six Sigma utilizes statistical analysis to minimize variation. Lean Six Sigma brings together the best of both worlds, leveraging Lean’s speed and waste reduction with Six Sigma’s rigor in eliminating defects.

In this post, we’ll compare Six Sigma vs Lean Six Sigma covering their core principles, tools, as well as applications of Lean, Six Sigma, and Lean Six Sigma to help you determine the best approach for improving processes and quality in your organization.

Six Sigma vs Lean Six Sigma Overview

Bottomline Upfront: The main difference between Six Sigma and Lean Six Sigma is that Six Sigma employs rigorous statistical tools and analysis to minimize defects and reduce process variation.

Lean Six Sigma combines this focus on defect reduction with Lean principles of maximizing value and minimizing waste through techniques like process mapping and workflow optimization. The integrated approach provides a comprehensive framework to achieve process excellence.

What is Six Sigma?

Six Sigma is a rigorous, data-driven methodology for eliminating defects and boosting quality.

First developed by Motorola in the 1980s, it utilizes statistical analysis and structured DMAIC (Define, Measure, Analyze, Improve, Control) or DMADV (Define, Measure, Analyze, Design, Verify) processes to achieve predictable, consistent results.

The central goal of Six Sigma is reaching a negligible defect level of 3.4 defects per million opportunities (DPMO). To accomplish this, Six Sigma focuses on minimizing variation in processes and enabling high-quality, uniform outputs.

Statistical techniques and metrics are applied through the DMAIC vs DMADV framework to fully understand process capabilities, pinpoint root causes of defects, and implement targeted solutions.

By relentlessly focusing on critical metrics and making data-driven decisions, Six Sigma enables fact-based process improvements that boost quality, efficiency, and competitive advantage.

Six Sigma Principles

The core principles of Six Sigma include:

  • Prioritizing critical metrics like defects per million opportunities (DPMO) and process sigma level
  • Applying statistical thinking to make data-driven decisions
  • Building organizational infrastructure to support quality gains
  • Utilizing structured project management methods for problem-solving
  • Aligning initiatives with key business goals and strategies

Adhering to these principles allows Six Sigma to deliver tremendous improvements in product and process quality, while also boosting efficiency and customer satisfaction through fact-based decision-making powered by statistical data.

What is Lean Six Sigma?

Lean Six Sigma integrates two process improvement methodologies Lean and Six Sigma. While Lean focuses on optimizing workflow and speed, Six Sigma employs rigorous statistical tools to minimize defects. Together, they enable organizations to enhance quality, eliminate waste, and deliver value for customers.

First developed in the early 2000s, Lean Six Sigma applies Lean’s culture of continuous improvement and waste reduction to the data-driven DMAIC framework of Six Sigma. This allows organizations to leverage the strengths of both approaches in a synergistic manner.

Lean Six Sigma projects utilize Lean tools like 5S, Kanban, and Kaizen to smooth workflow, while deploying Six Sigma tools like statistical process control and design of experiments to reduce variation.

With its combined emphasis on enhancing flow while also improving quality through data analysis, Lean Six Sigma provides organizations with an adaptable roadmap for achieving significant gains and fosters a culture of innovation centered on creating value for customers by eliminating waste and defects.

Lean Six Sigma Principles

The core principles of Lean Six Sigma include:

  • Maximizing value for customers by eliminating non-value activities
  • Using statistical data to understand process variation and defects
  • Fostering a culture of continuous improvement and employee engagement
  • Aligning projects with overarching business goals and strategies
  • Smoothing workflow and reducing waste through Lean tools
  • Reducing defects and variation with Six Sigma statistical tools
  • Focusing on critical metrics like cycle time, defects per million opportunities

Adhering to these principles allows Lean Six Sigma to deliver transformative improvements in quality, efficiency, speed, and bottom-line results.

Difference Between Six Sigma and Lean Six Sigma

While Six Sigma and Lean Six Sigma have some commonalities, there are key differences between the two methodologies:

Origins and Influences

Six Sigma originated at Motorola in the 1980s and was heavily influenced by statistics and engineering principles. Lean Six Sigma emerged later, combining Six Sigma with Lean manufacturing which traces its roots to the Toyota Production System and influence from Henry Ford.

Primary Focus

The core focus of Six Sigma is reducing variability and defects through rigorous statistical analysis. Lean Six Sigma blends this focus with Lean’s emphasis on eliminating waste and non-value activities to streamline processes.

Tools and Techniques

Statistical tools like process capability analysis, hypothesis testing, and design of experiments are integral to Six Sigma. Lean Six Sigma leverages these along with Lean tools like 5S, value stream mapping, and Kaizen.


Six Sigma targets achieving less than 3.4 defects per million opportunities (DPMO). Lean Six Sigma focuses on additional metrics like cycle time, lead time, takt time, and process speed.

Implementation Style

Six Sigma follows a structured define-measure-analyze-improve-control (DMAIC) or design-measure-analyze-design-verify (DMADV) sequence. Lean Six Sigma combines this statistical rigor with Lean’s continuous improvement culture.

Training and Certification

Six Sigma emphasizes extensive training and certification at green belt, black belt, and master black belt levels. Lean Six Sigma uses similar belt levels but places relatively less emphasis on formal certification processes.

Culture Created

Six Sigma instills a culture focused on statistical thinking, analysis, and precision. Lean Six Sigma incorporates this drive for analytical excellence with Lean’s culture of waste elimination and continuous improvement.

Similarities between Six Sigma and Lean Six Sigma

While having distinct approaches, Six Sigma and Lean Six Sigma share some key similarities:

Focus on Reducing Waste and Defects

Both Six Sigma and Lean Six Sigma aim to eliminate waste and defects in processes. Six Sigma does this by reducing variability while Lean focuses on streamlining workflow. Lean Six Sigma combines both techniques.

Seeking Continuous Improvement

Six Sigma and Lean Six Sigma foster a culture of continuous improvement and encourage employees at all levels to contribute ideas for process enhancements. They both aim for incremental gains over time.

Application of Statistical Tools

Statistical techniques like hypothesis testing, regression analysis, statistical process control, and design of experiments are leveraged extensively in Six Sigma. Lean Six Sigma draws on these analytical tools as well while adding Lean methods.

Structured Project Management

The DMAIC framework provides structured project management for focused problem-solving. Both Six Sigma and Lean Six Sigma adopt this approach for tackling improvement initiatives.

Customer-Centric Culture

Six Sigma and Lean Six Sigma instill a customer-first mindset, as enhancing value for customers is the overarching goal driving waste and defect reduction efforts. The Voice of Customer (VoC) is given importance.

When to Use Six Sigma vs Lean Six Sigma

Selecting the right process improvement methodology requires understanding the strengths of both Six Sigma and Lean Six Sigma. The suitability of each approach depends on the goals and needs of an organization.

When to Use Six Sigma

Six Sigma is advantageous in the following situations:

  • The primary goal is to achieve extremely high-quality levels, with defect rates under 3.4 defects per million opportunities. Six Sigma’s statistical rigor can help organizations reach these low defect rates.
  • There is high inherent process variation that requires detailed statistical analysis to understand, control, and reduce variation through techniques like statistical process control, capability analysis, and design of experiments.
  • Existing processes need incremental improvement and fine-tuning rather than radical redesign. Six Sigma’s DMAIC framework is designed for optimizing current processes.
  • Large volumes of data are available, but analytical rigor needs to be applied to data-driven decision-making. Six Sigma provides this analytical discipline.
  • Developing employees’ technical capabilities in statistical analysis and project management is important. Six Sigma training programs and belt certifications build these capabilities.
  • A culture focused on metrics, analytics, and precision needs to be established. Six Sigma instills this metrics-driven culture focused on reducing variation.

When to Use Lean Six Sigma

Lean Six Sigma delivers maximum impact in these situations:

  • Dramatic improvements in quality, cost, delivery, and flexibility are urgently needed. Lean Six Sigma provides a rapid, transformative approach.
  • Reducing waste through process mapping, workplace organization, inventory reduction, etc. is a high priority. Lean Six Sigma applies Lean techniques to eliminate waste.
  • Improving process speed, smooth workflow, and eliminating bottlenecks is important. Lean Six Sigma streamlines processes and value streams.
  • A culture of continuous improvement, employee empowerment, and cross-functional collaboration is lacking. Lean Six Sigma fosters this culture.
  • Aligning improvement efforts to business strategy and goals is critical. Lean Six Sigma’s focus on value and waste reduction provides this linkage.

Six Sigma vs Lean Six Sigma Certification: Which is Right for You?

Choosing the right certification depends on your goals and experience. Here is an overview of Six Sigma and Lean Six Sigma certification levels and differences:

Six Sigma Certification Levels

Six Sigma certifications recognize expertise across different belt levels:

  • Yellow Belts: They learn foundational Six Sigma principles and support projects in their department. This allows them to gain familiarity with the methodology.
  • Green Belts: They typically complete 1-2 weeks of classroom training to learn core statistical and DMAIC tools. They are equipped to lead smaller-scale projects requiring basic data analysis.
  • Black Belts: They receive extensive training in advanced statistical techniques like design of experiments and regression. They take on complex deployments and manage multiple Six Sigma projects and teams.
  • Master Black Belts: They possess deep technical capability and substantial experience leading high-impact Six Sigma initiatives. They train and mentor other belt holders and help deploy Six Sigma organization-wide.

Higher belt levels require increasing project experience, training, and capability in applying statistical tools to achieve process excellence.

Lean Six Sigma Certification Levels

Lean Six Sigma certifications include:

  • White Belt: They focus on fundamental Lean Six Sigma terminology, principles, and overview.
  • Yellow Belt: They learn process mapping, 5S, Kanban, DMAIC, and other core Lean and Six Sigma tools, and help with projects.
  • Green Belt: They lead hands-on improvement projects using the DMAIC roadmap, and develop proficiency in Lean and basic statistical tools.
  • Black Belt: They receive advanced training in statistical methods like design of experiments, and lead complex deployments managing multiple projects and teams.
  • Master Black Belt: They require deep cross-functional experience leading strategic Lean Six Sigma deployments. Also, they train and develop Black Belts and champion organizational adoption.

The belt-based certification structure is similar, but Lean Six Sigma includes training and project work in Lean methods in addition to Six Sigma statistical tools.

Understanding the certification levels helps identify the right option based on experience, expertise, and career goals in process excellence.


Whether you are just starting your journey in process improvement or are an experienced professional, understanding the distinctions between Six Sigma and Lean Six Sigma is key.

Both offer proven frameworks for enhancing quality and reducing waste and defects. While Six Sigma relies heavily on statistical tools, Lean Six Sigma incorporates techniques from both methodologies to optimize processes through structured problem-solving.

Evaluating your organization’s needs and priorities will determine which approach delivers the greatest business impact and value. With the right deployment, you can transform processes and create a culture of excellence.


Is Six Sigma and Lean Six Sigma the Same?

No, Six Sigma and Lean Six Sigma are not the same. While both focus on improving quality and efficiency, Six Sigma relies heavily on statistical analysis to reduce defects whereas Lean Six Sigma blends Six Sigma’s statistical tools with Lean principles like waste reduction and workflow optimization. Lean Six Sigma combines the two methodologies into an integrated approach.

When did Six Sigma become Lean Six Sigma?

Six Sigma originated in the 1980s and Lean manufacturing traces back to the 1950s, but the integrated Lean Six Sigma methodology emerged in the early 2000s. This combined Six Sigma’s rigorous data-driven approach to reduce defects with Lean’s focus on eliminating waste.

The blended Lean Six Sigma framework enabled organizations to achieve greater speed, quality, and efficiency gains than either approach could deliver independently

Is Lean Six Sigma Outdated?

No, Lean Six Sigma remains a relevant and powerful process improvement methodology. While originating in manufacturing, Lean Six Sigma’s focus on reducing waste, improving quality, and creating value has made it adaptable across many industries.

Its data-driven approach combined with Lean tools provides an effective framework for continuous improvement. and it continues to deliver value in today’s digital age.

Which Comes First Lean or Six Sigma?

Six Sigma was developed first as a distinct methodology by Motorola in the 1980s, focusing on reducing defects through statistical analysis. Lean originated earlier, evolving from the Toyota Production System’s emphasis on waste reduction beginning in the 1950s.

So the Six Sigma brand and methodology was created after Lean concepts, though the integrated Lean Six Sigma approach emerged later.

David Usifo (PSM, MBCS, PMP®)
David Usifo (PSM, MBCS, PMP®)

David Usifo is a certified project manager professional, professional Scrum Master, and a BCS certified Business Analyst with a background in product development and database management.

He enjoys using his knowledge and skills to share with aspiring and experienced project managers and product developers the core concept of value-creation through adaptive solutions.

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