Lean vs. Six Sigma: Two Sides of Operational Excellence

In the pursuit of excellence, businesses are always looking for ways to improve efficiency, deliver quality products or services, and increase customer satisfaction – while keeping costs low. This journey often leads to two popular methodologies: Lean and Six Sigma.

Lean advocates a mindset of Continuous Improvement, focusing on reducing waste and boosting efficiency in business or service cycles to create value for customers. Think of it like an ongoing process for reducing patient wait times in healthcare or streamlining software updates.

With Six Sigma, the goal is to reduce errors and variation for improved products and more efficient processes, resulting in higher customer satisfaction. It uses statistical analysis to find and correct defects in the manufacturing process or create standard operating procedures. Think of it as using data to pinpoint the cause of a defective car part or standardize the customer experience at a call center.

At times, these methodologies work independently. But often, they’re merged under the banner of Lean Six Sigma (LSS). Together, they provide a systematic approach to enhance efficiency, quality, and overall operational performance.

So, which path is right for you? The Continuous Improvement of Lean, the data analysis of Six Sigma, or the combination of both in Lean Six Sigma?

Let’s compare and find out!

An Introduction to Lean

Lean is a process improvement toolkit, a philosophy, and a mindset. It seeks to reduce waste while maximizing efficiency and value within a process.

Lean focuses on matching production with demand by supplying orders in a “just-in-time production.” Although Lean principles originated in manufacturing (going back to Henry Ford’s automobile production line), every industry that strives to reduce lead times and costs, and improve product quality uses them.

The goal of Lean thinking is to align with value to the customer and find ways to use “less of everything” so you can create a maximum amount of value.

An essential aspect of Lean that helps with this is visualizing and understanding the entire value stream. With tools like Value Stream Mapping (VSM), you can see the flow of materials and information from the inception of a product or service to its final delivery to the customer.

This visualization makes it easy to identify both inefficiencies and opportunities for improvement, helping guide your organization toward more efficient and responsive processes.

Although you might view waste reduction as the core of Lean, I see its most powerful benefits as a cultural shift toward delivering customer value and Continuous Improvement. Not only does the organization make a greater impact, but each individual becomes more engaged by applying their talents. 

An Introduction to Six Sigma

Six Sigma is a systematic, process-improvement strategy that seeks to improve output quality by identifying and removing causes of defects and variability.

It’s a statistical concept that measures how far a process deviates from perfection. Think of Six Sigma as a goal, where processes encounter fewer and fewer defects to produce the best experience for a customer. You can achieve this goal by aligning CTQs (Critical to Quality) – standard Six Sigma performance requirements – to your organization’s processes.

One of the cornerstones of Six Sigma projects is the systematic methodology known as DMAIC, which guides practitioners through the stages of:

  • Define – clearly outline project goals and document customer requirements
  • Measure –involves data collection to quantify the current state of the process
  • Improve – oversee the implementation of solutions that lead to measurable enhancements
  • Analyze – use statistical tools to identify root causes of issues and inefficiencies
  • Control– establish measures to ensure the sustainability of improvements over time

Central to Six Sigma is the emphasis on customer requirements and satisfaction.

The core of Six Sigma is systematic improvement by using data. However, when organizations successfully adopt it, they create a more curious, collaborative, and problem-solving culture. It may be driven by numbers, but it deeply engages everyone involved to understand the root causes of problems and find the best solutions.

Notable Differences Between Lean and Six Sigma

A natural synergy exists between Lean and Six Sigma. While both lead to company and process improvements, each approach has separate foundations in its methodology.

Here’s a quick summary of Lean and Six Sigma.

Lean is all about simplicity and flow, looking for quick wins and small, incremental improvements through rapid changes.

Six Sigma is focused on removing defects and variations to improve product quality and ensure customer satisfaction.

While the quick wins of Lean are appealing, Six Sigma’s strength lies in identifying the root cause of a problem and identifying the correct solution.

Let’s walk through some more key differences between Lean and Six Sigma:

Focus and Objectives

The primary objective of Lean is to optimize processes to deliver maximum value to the customer.

The primary objective of Six Sigma is to improve quality and reduce defects by minimizing process variation.


Lean may follow several different methodologies. Two of the most common are:

  • Agile methodology – a set of principles to improve efficiency by eliminating waste and increasing value.
  • PDCA methodology – (Plan, Do, Check, and Act) is based on the Scientific Method and identifies steps to implement change.

Six Sigma projects generally follow one of two project methodologies:

  • DMAIC methodology – (Define, Measure, Analyze, Improve, Control), used for projects with the goal of improving an existing business process.
  • DMADV methodology – (Define, Measure, Analyze, Design, and Verify), used for projects with the goal of creating new process or product designs.

Problem-Solving Approach

Both Lean and Six Sigma create a problem-solving culture when implemented at all levels.

Lean is a mindset focused on continually improving problem-solving methods. Lean practitioners use Continuous Improvement to discover methods that reduce waste and optimize processes to increase the value delivered to the customer.

Six Sigma is a structured and deliberate technique that solves organizational challenges by using data to reduce risk and process variability. It does this by following each step of the DMAIC or DMADV methodology.

Let’s start with a key definition for any business – waste. What do you consider waste in a process?

In Lean, waste is any activity or process that does not add value to the customer. It could be unnecessary movement of people, like nurses running to get the supplies they need. To try and solve this, you might move the most commonly used supplies to a central location near triage.

8 Wastes Infographic

In Six Sigma, waste is anything that leads to defects or deviations from the desired outcome. This definition is broader to incorporate things like variations in how a process is completed or the types of tools used to complete it. Like using different recipes for the same cookie, they might look the same but the taste won’t be standardized. To solve this, you would use the same recipe, ingredients, and tools to ensure all cookies have the same great taste your customers love.

Tools and Techniques

Lean has several techniques to help with efficiency, including:

  • PDCA establishes a rapid cycle improvement method.
  • A3 describes a process problem, the root cause analysis, and potential countermeasures.
  • 5S organizes the workplace for efficiency, cleanliness, and safety via:
    • Sort
    • Set in Order
    • Shine
    • Standardize
    • Sustain
  • 8 Wastes diagnose the top eight elements that get in the way of process flow. A good way to remember this is with the acronym DOWNTIME:
    • Defects
    • Overproduction
    • Waiting
    • Non-Utilized Talent
    • Transportation
    • Inventory
    • Motion
    • Extra-Processing
  • Value Stream Mapping identifies value or non-value activities in a process.
  • Flow (or Continuous Flow) shows the unimpeded movement of a process and reduces lead time.
  • Pull allows customer demand to dictate process flow.
  • Spaghetti Maps provide a visual display of the wasted motion of individuals in a given workspace.
  • Process Walks detail where work occurs, as identified by those who work in the process.
  • Batch Sizing classifies the smallest number of units to efficiently process at a time.
  • Standard Work documents the agreed-upon best method to accomplish a given task.
  • Work Cell Design establishes the workspace layout that results in the least amount of wasted motion for the workforce.
  • Single-Piece Flow provides a process for individual units as opposed to creating batches.
  • Kaizen encourages employees to find small, incremental improvements to processes.

Six Sigma has a number of its own techniques to support data-driven problem-solving. Some examples include:

  • DMAIC provides a five-step process improvement method.
  • Project Charter lays out the process problem, goal, scope, timeline, and basic outline of an improvement project.
  • Data Collection Plan establishes a guide to what data will be collected, by whom, how, and when.
  • Basic Statistics measure any data set’s average, median, range, and standard deviation.
  • Histogram forms a graph that provides a snapshot of a data set displaying the spread, shape, average, and range.
  • Pareto Chart creates a cascading bar chart to display the sources of process issues from the biggest source to the smallest.
  • Measurement Systems Analysis documents a way to test the accuracy, repeatability, reproducibility, and precision of data collection.
  • Hypothesis Testing identifies a way to provide statistical rigor to theories about the root causes of process issues.
  • Design of Experiments devise controlled tests to assess the effectiveness of different ways to run a process to pick the best conditions, materials, and methods.
  • Statistical Process Control monitors a process to ensure that it consistently meets customer requirements.
  • Control Charts identify shifts and trends in a process.
  • Critical to Quality requirements reflect the Voice of the Customer (VOC).
  • Process Maps visualize the flow of a process.
  • 5 Whys helps to uncover the underlying cause of an issue.
  • Fishbone Diagrams categorize potential causes of problems.

Lean and Six Sigma: Leading Organizations Use Them Together

While Lean and Six Sigma have traditionally been taught as separate methodologies, the boundary between them has become less defined. This has led to combining Lean and Six Sigma teachings as “Lean Six Sigma” to reap the best of both philosophies.

Lean Six Sigma provides a systematic approach and a combined toolkit to help organizations build their problem-solving muscles, making Continuous Improvement a daily practice.

Both approaches and their toolkits are extremely valuable when solving problems. It doesn’t matter where a tool comes from – Lean or Six Sigma – as long as it does the job. We’ve helped 6,000+ organizations around the world launch LSS programs. If you want the same competitive advantage, explore our free training for you or your team.

By combining both methods, you can apply the right mindset, tactics, and tools to solve any problem.

GLSS’ optimized approach to integrating Lean and Six Sigma delivers 14x ROI faster than other, outdated approaches.

In addition to:

  • $213k average financial savings per project
  • 55% average reduction in downtime
  • 54% average reduction in processing time
  • 53% average defect reduction
  • 61% average increase in production

Common Benefits of Using Lean and Six Sigma Together

Using Lean and Six Sigma together, or as Lean Six Sigma (LSS), provides you with a competitive advantage. Some benefits when Lean and Six Sigma are combined include:

Stronger Customer Focus

LSS significantly improves customer focus through Continuous Improvement and product or service efficiency. You can accomplish this by identifying and delivering value from the customer’s perspective.

Live in a constant state of awesomeness!

– Kimberly Fleming

Engaged Workforce

LSS promotes a culture of Continuous Improvement where employees are encouraged to identify inefficiencies and contribute ideas for enhancement. This involvement in problem-solving fosters a sense of ownership and pride in work, leading to higher levels of engagement.

Customers will never love a company unless employees love it first.” – Simon Sinek

Problems Solved at the Root

LSS is based on data-driven decision-making and incorporates various root cause analysis techniques such as Fishbone Diagrams, 5 Whys, and Pareto Analysis to identify and correct underlying issues accurately.

Why is it that we never have enough time to do it right the first time, but we always have enough time to do it over?” – Jack Bergman

Error Reduction

LSS systematically identifies and eliminates waste, including defects or errors. Some methods include implementing checks, visual cues, or automation to standardize processes and reduce variation, which significantly contributes to errors.

The only real mistake is one from which you learn nothing.” – Henry Ford

Increased Capacity

LSS increases capacity within organizations by optimizing processes, eliminating waste, and enhancing overall efficiency. The primary methods focus on streamlining operations, minimizing variation, and reducing non-value-added activities.

The future depends on what we do in the present.” – Mahatma Gandhi

Greater Efficiency

LSS enhances efficiency by focusing on waste elimination and process optimization, streamlining operations, and making data-driven decisions focusing on variation reduction.

Efficiency is doing better what is already being done.” – Peter Drucker

Minimized Costs

LSS is designed to enhance cost-effectiveness and resource utilization. This is achieved by eliminating non-value-added activities, reducing cycle times, cross-training employees, and standardizing processes.

Creativity before cash!” – Mike Osterling

Maximized Profits

LSS contributes in numerous ways to maximizing profits by identifying waste and methods to lower operational costs, focusing on consistent quality, forecasting, reducing inventory, and delivering efficient resource allocation.

Profit in business comes from repeat customers. Customers that boast about your product or service and bring friends with them.” – W. Edwards Deming

Operational Excellence

LSS plays a pivotal role in achieving Operational Excellence. It instills a mindset in organizations to continually improve processes, reduce waste, enhance quality, and foster a culture of excellence across all aspects of operations.

We are what we repeatedly do. Excellence, then, is not an act, but a habit.” – Aristotle

Optimize Before Automating

“Organizations often make the mistake of automating poorly performing processes before optimizing them – resulting in much more of the same (undesirable) outcomes, but faster. LSS helps optimize processes at their core so truly better products and services are delivered – faster and more cost-effective.” — Karlo Tanjuakio, Founder & CEO at GLSS

Additional considerations include:

  • Streamlining processes results in improved customer experience and increased loyalty.
  • Developing more efficient process flows drives higher bottom-line results.
  • Switching from defect detection to defect prevention reduces costs and removes waste.
  • Standardizing processes leads to organizational “nimbleness” and the ability to pivot to everyday challenges.
  • Decreasing lead times increases capacity and profitability.
  • Engaging employees in an effort improves morale and accelerates individual development.

Ready to Start Your Lean Six Sigma Journey?

Remember: Lean and Six Sigma are two great toolkits, and together, they provide all the support you need to delight customers, reduce costs, and build strong teams.

“All boats lift with the rising tide. You, too, can lift yourself by knowing when to use the right technique at the right time. Global organizations use Lean and Six Sigma together to solve problems and deliver measurable improvement. GLSS gives you those same skills to deliver the greatest possible impact.” — Karlo Tanjuakio, Founder & CEO at GLSS

There’s an exciting road ahead, and an easy way to begin this adventure is to sign up for the highest-rated Lean Six Sigma training available.

Get a free trial of GLSS training for you or your team to start your process improvement journey today!


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