Difference Between Six Sigma and Lean

The terms “Six Sigma” and “Lean” are very often used in businesses as both of them define certain methodologies to achieve more efficiency. Though they aim to suggest techniques and tools that are for the overall improvement of the organization, these methods vary. It is important to study these techniques widely before approaching one for your business.

Six Sigma vs Lean

The main difference between six sigma and lean is that six sigma tries to reduce the number of variabilities so that as a result the defects are removed from a system. On the other hand, lean focuses more on optimizing every process such that the time taken in both production and response to the customer is reduced.

Six Sigma and Lean

Six sigma mainly focuses on eliminating defects such that the manufacturing defects should not be more than 3.4 occurrences per million units or events. It is used in various businesses to eliminate waste and boost their profit. One needs to understand statistics and financial analysis to practice six sigma.

Lean is an enterprise production principle according to which any component of a business that doesn’t add any value to the final product is unwanted. It mainly focuses on eliminating every inefficient factor in the production process and ultimately increasing the value of the products.

Comparison Table Between Six Sigma and Lean

Parameters of ComparisonSix SigmaLean
DefinitionSix Sigma is a business management methodology where it wants to reduce defects to not more than 3.4 per million events.  Lean is also a business management methodology that states that any business company directly not adding value to the final product is redundant.
HistoryThe concept of six sigma was created by an engineer called Bill Smith in Motorola in 1986.The origin of the lean manufacturing concept is from the Japanese company Toyota. It was derived in the 1930s from their model, “The Toyota Way.”
GoalThe main goal of six sigma is to improve quality by removing defects and errors.The main goal of lean management is to optimize every process and resource and add more value for the customers.
PracticeSix Sigma is more of a technical, methodical, and structural approach that is followed step-by-step.The concept of lean is more like a set of principles that can be followed by anyone for smart decision-making.
LeadershipThere are specific roles for everyone at different levels of the company who practice six sigma implementations.There is more fluidity in lean management and everyone is allowed to contribute in the same way.
FunctionSix Sigma is implemented in various sectors from manufacturing to customer services.Lean manufacturing is applied to optimize processes and thus it is very common for the IT sectors.

What is Six Sigma?

Different types of management processes have different methods to solve a complicated business problem but the goal is the same. Every company has the same goal to boost profit, minimize defects, and improve overall performance. The six sigma methodology focuses on statistical improvements for improving the overall business functions. Learning how to implement the six sigma principles requires a training program as it is a very structured approach that has multiple levels.

The six sigma practitioners follow certain steps to implement this concept and it is called DMAIC in short. The abbreviation DMAIC stands to define, measure, analyze, improve, and control. At first, the company spots a faulty process with the help of data analysis and makes a rough outline of the problem and the goal. After this, the current performance of the process is observed and a list of inputs that might be the cause of the faults. Each input is analyzed individually to know the root cause and then the entire team works to improve that particular process. And the last step is to add controls to the process and make sure it doesn’t become ineffective after some time.

There are several levels of the six sigma certification that are categorized by different colors of the belt. There are four levels, white belt (lowest level), yellow belt, green belt, and black belt (expert).

What is Lean?

Several companies use lean manufacturing principles today to remove waste. In a business that approaches that lean method, recognizing various types of wastes are important. Lean is focused on removing waste from every sector and optimizing the overall system to create more value for the customer. It considers every business element superfluous that doesn’t contribute to adding value for the customers. There are seven main waste categories, namely, inventory, motion, transport, waiting, over-processing, overproduction, and defects.

Lean helps in developing various aspects of a business by eliminating waste. For example, lean will try to optimize the space required for production, increase the speed of delivery, establish a better relationship with the suppliers, etc. Since lean is mainly about optimizing various processes and inputs, its implementation is mainly in the software division of any business. Lean management is more like a continuous process to ensure constant improvement. Lean helps in better use of resources and create an intelligent business process.

There are mainly five principles of lean management. The first step is identifying value (finding problems of the customer and how can a product and value) followed by value stream mapping to understand the workflow. Breaking the work process to simplify the workflow followed by developing a pull system, and then securing continuous improvement.

Main Differences Between Six Sigma and Lean

  1. The concept of six sigma was started by an engineer working for Motorola whereas lean is an original idea of the Japanese company, Toyota.
  2. The main goal of six sigma is to improve quality by removing defects and errors whereas the main goal of lean management is to optimize every process and resource.
  3. Six Sigma is more of a technical, methodical, and structural approach that is followed step-by-step whereas lean is more like a set of principles that can be followed by anyone for smart decision-making.
  4. Six sigma is applied to solve more complicated organizational problems whereas lean can be introduced to improve overall efficiency.
  5. Six sigma is a very methodical and structural management approach whereas lean is more like a set of principles anyone can follow.
  6. The leadership among six sigma practitioners works in a hierarchal way whereas anyone can contribute in the same way in lean manufacturing.


It is possible that six sigma and lean management can co-exist in a single corporation. But before trying to approach any of the management methods, understanding the core values of your business and your customer base is very important. Your business model should have a good sync with the goals that these methodologies can provide. Several big multinational companies follow either of these management techniques today. For example, companies like Bank of America, General Electric, Amazon, etc. have successfully implemented six sigma. On the other hand, Nike, Ford, and Intel are some companies that use lean principles.


  1. https://www.sciencedirect.com/science/article/pii/S0166497204001828
  2. https://www.sciencedirect.com/science/article/pii/S2212567116302349
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