Best certifications
Quality and Lean Six Sigma certifications: what they mean and who issues them
Belts, accredited certifications and quality credentials explained, and how to judge which ones employers trust.
Lean Six Sigma remains one of the most popular improvement methods in manufacturing, energy and services. But "belts" are issued by many organisations with very different standards. This guide explains the method, the belt system and how to identify credible certifications.
How this list was made. This is an editorial shortlist of established certifications described from their issuers’ public information. We do not rank them, and fees, formats and requirements change. Confirm details with the issuer before applying.
The method
Six Sigma (6σ) is a set of techniques and tools for process improvement.2 It was introduced by American engineer Bill Smith while working at Motorola in 1986.2 Six Sigma strategies seek to improve manufacturing quality by identifying and removing the causes of defects and minimizing variability in manufacturing and business processes.2 Lean Six Sigma is a process improvement method that uses a collaborative team effort to improve performance by systematically removing operational waste and reducing process variation.1
Why issuers matter
There is no single owner of Six Sigma, so belts vary from short online courses to rigorous exams with project requirements. A useful benchmark is the ASQ Certified Six Sigma Black Belt. ASQ lists the requirement of Three years of work experience and one completed project with a signed affidavit (or two projects).3 The exam is 165 questions of which 150 scored, 4 hours 18 minutes, open book.3 And it is ANAB accredited to ISO/IEC 17024.3 — a sign of independent oversight.
Questions to ask
- Does the belt require a real project, and is it reviewed?
- Is the exam proctored, and is the body accredited?
- Is the issuer recognised by employers in your sector?
Using it well
Belts deliver value through projects. Pick problems with measurable impact on safety, quality, energy or cost, and follow the method with data. Combine with Lean tools such as 5S and value stream mapping for quick wins.
The DMAIC cycle
DMAIC or define, measure, analyze, improve and control (pronounced də-MAY-ick) refers to a data-driven improvement cycle used for optimizing and stabilizing business processes and designs.4 The DMAIC improvement cycle is the core tool used to drive Six Sigma projects.4 In the Define step, the purpose of this step is to clearly pronounce the business problem, goal, potential resources, project scope, and high-level project timeline.4 Measure establishes baseline performance and checks the measurement system; Analyze finds root causes with data; Improve tests and implements solutions; Control sustains the gains with control plans and monitoring.
The method is not restricted to Six Sigma: DMAIC is not exclusive to Six Sigma and can be used as the framework for other improvement applications.4
Origins and issuers
It was introduced by American engineer Bill Smith while working at Motorola in 1986.2 Lean Six Sigma is a process improvement method that uses a collaborative team effort to improve performance by systematically removing operational waste and reducing process variation.1 There is no single owner of belt certifications. Professional societies are one type of issuer: the American Society for Quality (ASQ), formerly the American Society for Quality Control (ASQC), is a society of quality professionals, with more than 30,000 members, in more than 140 countries.5 Universities, consultancies and companies also issue belts, with widely varying rigour.
What the belt levels usually mean
| Level | Typical role | Typical evidence |
|---|---|---|
| Yellow | Team member aware of the method | Short course, quiz |
| Green | Leads small projects part-time | Course, exam and often one completed project |
| Black | Leads complex projects, coaches green belts | Extended training, exam, multiple projects with verified results |
| Master black | Programme leader and trainer | Black belt experience, coaching and programme record |
These are common patterns, not a standard; read the specific issuer's requirements.
Evaluating a programme
- Project requirement: does certification require a real project with financially validated results?
- Exam: is it proctored, and does it test statistical application rather than terminology?
- Body of knowledge: is it published and comparable to recognised bodies of knowledge?
- Accreditation: is the personnel certification accredited to ISO/IEC 17024 or recognised by employers?
- Software skills: does training include hands-on statistical analysis?
Quality management credentials beyond belts
Quality professionals may also need auditor qualifications for management system standards such as ISO 9001, often through schemes that register auditors at different grades. Combining a belt with auditor training gives both improvement and assurance skills.
Making the certificate pay off
Organisations get value when belts work on strategic problems with sponsors who remove obstacles. Track realised savings and quality improvements after projects close, and recognise teams publicly.
Lean and Six Sigma together
Lean Six Sigma is a process improvement method that uses a collaborative team effort to improve performance by systematically removing operational waste and reducing process variation.1 Lean tools address flow, waiting and inventory; Six Sigma tools address variation and defects. Many problems need both: a line can have long waiting times and also high scrap.
Core tools a green belt should use confidently
| DMAIC phase | Tools |
|---|---|
| Define | Project charter, SIPOC, voice of the customer |
| Measure | Data collection plans, measurement system analysis, process capability |
| Analyze | Pareto charts, cause-and-effect diagrams, hypothesis tests, regression |
| Improve | Experiments, pilot tests, mistake-proofing |
| Control | Control charts, control plans, standard work |
Remember that all of the DMAIC process steps are required and always proceed in the given order.4 Skipping Measure is the most common shortcut and the most common reason projects fail to hold their gains.
Professional societies
ASQC was established on 16 February 1946 by 253 members in Milwaukee, Wisconsin, with George D.5 Edwards as president. The organization was first created as a way for quality experts and manufacturers to sustain quality-improvement techniques used during World War II.5 National quality bodies in other countries offer similar communities, events and certifications.
Building an internal programme
- Choose projects linked to strategic goals with an executive sponsor.
- Train in waves, with each trainee working on a live project during the course.
- Provide coaching from experienced black belts.
- Have finance validate savings.
- Certify only after the project shows sustained results.
Evidence to keep
Keep a project portfolio for each belt: the charter, baseline data, analysis, solutions, control plan and validated results, plus a sponsor sign-off. This portfolio is often more convincing to employers than the certificate, and it is useful if you later apply to a more rigorous certifying body.
Key takeaways
- Belt quality varies widely; check issuer, exam and project requirements.
- Accredited certifications like ASQ CSSBB provide independent assurance.
- Value comes from completed improvement projects.
Frequently asked questions
Is a Green Belt enough?
For many roles, yes. Black Belts lead complex projects and coach others.
Are online belts worthless?
Not necessarily, but check whether they include proctored exams and project review.
What is ISO/IEC 17024?
A standard for bodies that certify people, used as a basis for accreditation.
Is an online-only belt credible?
It can be, if it includes a proctored exam and a real project; otherwise it mainly shows awareness.
Lean or Six Sigma first?
Many start with lean basics for flow and waste, then add Six Sigma statistical tools for variation problems.
Do belts expire?
It varies by issuer. Some require recertification; others are lifetime. Check before choosing.
Which software is used?
Statistical packages and spreadsheets are both common; what matters is understanding the statistics behind the outputs.
Sources
Every factual statement marked with a number links to the source below. Sources were retrieved on 23 October 2026; check the publisher for later revisions.
- Lean Six Sigma (Wikipedia) en.wikipedia.org
- Six Sigma (Wikipedia) en.wikipedia.org
- ASQ Six Sigma Black Belt asq.org
- DMAIC (Wikipedia) en.wikipedia.org
- American Society for Quality (Wikipedia) en.wikipedia.org
