What is Lean Six Sigma in simple terms?

Lean Six Sigma is a disciplined method for eliminating waste (Lean) and variation (Six Sigma) from how work moves through a business, using the DMAIC cycle — Define, Measure, Analyze, Improve, Control.

What are the Lean Six Sigma belts?

Yellow Belt is awareness, Green Belt leads projects part-time, Black Belt leads full-time and coaches Green Belts, and Master Black Belt trains and coaches Black Belts. Belts are earned through training plus documented project savings.

DMAIC is the five-step Six Sigma project cycle: Define the problem, Measure the current process, Analyze the root causes, Improve the process, and Control it so the improvement stays in place.

When should a company use Lean Six Sigma?

Use Lean Six Sigma when you have measurable defects, rework, or throughput problems, when cost of quality is a meaningful percentage of revenue, or when you need documented process discipline for an ISO or SOC 2 certification.

Lean Six Sigma: Definition, Belts, and When It's Worth Deploying

Lean Six Sigma is a disciplined method for eliminating waste and variation from how work moves through a business. Here's what the belts mean, what the method actually does, and when it's worth deploying.

George Fassett, Jr. · July 13, 2026

Lean Six Sigma is a disciplined method for improving how work moves through a business by eliminating two specific things: waste (Lean) and variation (Six Sigma). It was popularized by manufacturers — Toyota for Lean, Motorola and GE for Six Sigma — but the discipline applies to any operation where throughput, quality, and cost matter.

The Short Version

Lean targets waste — anything the customer wouldn't pay for. Waiting, rework, over-processing, excess inventory, unnecessary motion, defects, overproduction, and unused talent.
Six Sigma targets variation — the inconsistency in a process that produces defects and unpredictable outcomes.
Combined, they give an operator a language and a method for naming, measuring, and fixing the specific parts of a process that quietly cost the business the most.

The DMAIC Framework

Six Sigma projects follow a five-step cycle called DMAIC:

Define — the problem, the customer impact, and the scope.
Measure — how the process performs today, with real data.
Analyze — the root causes of the defect or waste.
Improve — the changes that eliminate them.
Control — the discipline that keeps the improvement in place.

If a "Lean Six Sigma project" doesn't finish with a written control plan, it isn't a Lean Six Sigma project. It's a suggestion.

The Belt System

Yellow Belt — awareness of the vocabulary and method.
Green Belt — leads projects part-time as part of a regular role.
Black Belt — leads full-time, coaches Green Belts, owns the harder projects.
Master Black Belt — trains and coaches Black Belts across an organization.

Belts are earned through training and completed projects with documented savings. A Black Belt without projects is a certificate, not a credential.

When Lean Six Sigma Is Worth Deploying

You have a delivery process with measurable defects, rework, or throughput problems.
Your cost of quality (rework, warranty, returns, customer credits) is a meaningful percentage of revenue.
You have variation in cycle time, close time, or first-pass yield that customers or the P&L feel.
You are preparing for an ISO, SOC 2, or industry certification and need documented process discipline.

When Lean Six Sigma Is Overkill

The problem is strategic, not operational — Lean Six Sigma won't fix a bad market or a bad product.
The organization is too small to sustain a control plan — a good written SOP is often enough.
You need to make a decision this week — DMAIC projects take weeks to months.

Mebuis engagements are led by George Fassett, a Lean Six Sigma Black Belt with U.S. Patent #6,532,481 and a TCU MBA. Lean Six Sigma discipline shows up throughout our Fractional COO and Business Assessment work. Book an operator alignment call if you want to talk through where the constraint in your process actually sits.

Frequently Asked Questions

What is Lean Six Sigma in simple terms?: Lean Six Sigma is a disciplined method for eliminating waste (Lean) and variation (Six Sigma) from how work moves through a business, using the DMAIC cycle — Define, Measure, Analyze, Improve, Control.
What are the Lean Six Sigma belts?: Yellow Belt is awareness, Green Belt leads projects part-time, Black Belt leads full-time and coaches Green Belts, and Master Black Belt trains and coaches Black Belts. Belts are earned through training plus documented project savings.
What is DMAIC?: DMAIC is the five-step Six Sigma project cycle: Define the problem, Measure the current process, Analyze the root causes, Improve the process, and Control it so the improvement stays in place.
When should a company use Lean Six Sigma?: Use Lean Six Sigma when you have measurable defects, rework, or throughput problems, when cost of quality is a meaningful percentage of revenue, or when you need documented process discipline for an ISO or SOC 2 certification.

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