Prep
Six Sigma vs PMP: different jobs, not different levels
Six Sigma vs PMP is not a choice between a junior and a senior credential. They certify different skills.
- PMP (Project Management Professional) is issued by the Project Management Institute (PMI). It covers how to lead people, run the delivery process and handle the business context of a project, across predictive, agile and hybrid approaches.
- Six Sigma is a data-driven method for reducing defects and variation in processes. Certifications come in belts, most commonly Green Belt and Black Belt, and test your ability to run improvement projects using statistical tools and the DMAIC cycle (Define, Measure, Analyze, Improve, Control).
There is overlap: a Six Sigma improvement effort is a project, and a project manager benefits from measuring quality. But the PMP is about delivering any project on time and within scope, while Six Sigma is about making an existing process measurably better.
| PMP | Six Sigma (ASQ or IASSC belts) | |
|---|---|---|
| Focus | Leading projects | Improving processes with data (DMAIC) |
| Issuer | PMI only | No single owner; ASQ and IASSC are two independent bodies |
| Experience needed | 24 to 60 months leading projects | ASQ: 3 years; IASSC: none |
| Exam fee (USD) | 445 / 675 (secondary sources) | IASSC 350 to 450; ASQ 483 to 585 non-member |
| Renewal | 60 PDUs every 3 years | Varies: ASQ Green Belt lifetime, ASQ Black Belt every 3 years |
Who issues Six Sigma certifications?
This is the most important difference. The PMP has one owner, PMI, with one exam and one set of rules. Six Sigma has no central owner. Many organisations, training companies and employers issue belts, and their standards vary widely. Two widely recognised independent bodies are:
- ASQ (American Society for Quality), which requires documented work experience and, for the Black Belt, completed projects with signed affidavits.
- IASSC (International Association for Six Sigma Certification), which certifies knowledge through an exam only, with no experience prerequisite.
Before you pay for any Six Sigma certification, check who issues it, whether there is an independent proctored exam, and whether employers in your field recognise it. A belt from a short course with no proctored exam carries much less weight. Facts below come from ASQ's and IASSC's own pages, checked in November 2026.
Comparison table: PMP vs ASQ and IASSC belts
| PMP (PMI) | ASQ Green Belt (CSSGB) | ASQ Black Belt (CSSBB) | IASSC Green Belt | IASSC Black Belt | |
|---|---|---|---|---|---|
| Prerequisites | 24 to 60 months leading projects (by education) plus 35 hours of training | 3 years of full-time, paid on-the-job experience in the Body of Knowledge areas | 3 years of full-time, paid experience plus 1 project with signed affidavit or 2 projects with affidavits | None | None |
| Questions | 180 (170 scored) | 110 (100 scored) | 165 (150 scored) | 100 graded (some forms add up to 10 ungraded) | 150 graded (some forms add up to 15 ungraded) |
| Exam time | 240 minutes | 4 hours 18 minutes | 4 hours 18 minutes | 3 hours | 4 hours |
| Book policy | - | Open book | Open book | Closed book | Closed book |
| Passing score | Not published | Not published (pass/fail) | Not published (pass/fail) | 70% | 70% |
| Exam fee (USD) | 445 member / 675 non-member (secondary sources) | 483 non-member; members save 100 | 585 non-member; members save 100 | 350 | 450 |
| Renewal | 60 PDUs every 3 years plus fee | Lifetime, no recertification | Every 3 years: 18 recertification units or retake the exam | Recognised perpetually; "current" status lasts 3 years under IASSC's recertification policy | Same as Green Belt |
ASQ times are for the computer-delivered exam, which is English only; a paper version is offered in Mandarin in some locations. The PMP fee is not shown on a current pmi.org page we could access: secondary sources report USD 445 for PMI members and USD 675 for non-members since August 2026, and PMI notes prices vary by region. PMP facts come from PMI's July 2026 Exam Content Outline and certification handbook.
What each exam tests
PMP
Three domains: People (33%), Process (41%) and Business Environment (26%). Questions are mostly scenarios where you choose the best action for a project manager, across predictive, agile and hybrid settings. Since July 2026 the exam includes case-study sets and graphic-based questions. Our how hard is the PMP guide goes into detail.
Six Sigma
Belt exams follow the issuing body's Body of Knowledge, built around DMAIC. Expect statistics. Typical topics include measuring process performance and capability, analysing variation and root causes, and controlling a process once it has improved, with Black Belt exams going deeper into analysis and into leading improvement projects. Check the issuer's Body of Knowledge for the exact list. ASQ exams being open book does not make them easy; you still need to apply the methods under time pressure.
Checklist: how to vet a Six Sigma certification
Because anyone can issue a Six Sigma belt, run through these questions before you pay. The PMP does not need this step, since PMI is the only issuer.
- Who issues it? An independent certifying body, a training company, or your employer? An independent body that does not sell the training is easier for employers to trust.
- Is there a proctored exam? A certificate of course completion is not the same as passing a supervised exam.
- Is the Body of Knowledge published? ASQ, for example, defines each belt by a Body of Knowledge that its experience requirement and exam refer to. If an issuer cannot show you what its exam covers, you cannot tell what the belt means, and neither can an employer.
- Does it require real projects? ASQ's Black Belt needs signed project affidavits. Experience-based belts show more than knowledge-only ones.
- Does it renew? Some belts are lifetime, others need recertification. Check the rules and costs up front.
- Do employers ask for it? Search job ads in your field and region and note which issuers they name. That is the best guide to what a belt is worth to you.
Which should you choose?
This is our editorial recommendation, not guidance from PMI, ASQ or IASSC.
| Your situation | Our pick | Why |
|---|---|---|
| You lead projects (IT, construction, marketing, product) | PMP | It certifies exactly what you do, and it is widely requested in project manager job ads. |
| You work in manufacturing, operations, supply chain or healthcare quality | Six Sigma Green Belt, then Black Belt | Process improvement is the core of those roles. |
| You lead improvement projects full time | ASQ Black Belt | Its project affidavit requirement proves real results, not just exam knowledge. |
| You want a Six Sigma credential but lack experience | IASSC Green Belt | No prerequisites; it proves knowledge while you build experience. |
| You do not yet meet PMP experience rules | CAPM, or a Six Sigma Green Belt if your work is operational | See PMP vs CAPM. |
| Operations manager running change projects | Both, PMP first if you lead the projects | They complement each other well. |
Can you hold both?
Yes, and some people in operations leadership do. The combination works because the PMP covers how to run a project and manage stakeholders, while Six Sigma covers how to find and fix the root cause of a process problem. If your goal is to lead improvement programs, the pair is stronger than either alone.
If you are deciding which to do first, start with the one that matches your current job. Your daily work becomes study material, and for the PMP and ASQ belts, your experience is a formal requirement anyway.
Cost and effort compared
The cheapest route to a recognised credential is an IASSC Green Belt at USD 350 with no prerequisites, though you will need to learn the statistics on your own or through a course. The PMP is the most involved: experience, 35 training hours, an application with possible audit, a four-hour exam and ongoing PDUs. ASQ belts sit in between on cost but require years of documented experience.
Remember the hidden costs: PMI membership if you want the member exam rate, ASQ membership for its discount, training hours for the PMP, and statistical software practice for Six Sigma. Our PMP exam cost page breaks down PMI fees in detail.
Ready to test your project management knowledge? Try the free PMP practice test.