Lean Six Sigma Black Belt Certification Practice Test

What the Lean Six Sigma Black Belt Certification is and how it works

According to IASSC, “The IASSC Certified Lean Six Sigma Black Belt Exam™ is a 150 question, closed book, proctored exam”^[1]

The IASSC Certified Lean Six Sigma Black Belt exam checks whether you can run an improvement project through the Define, Measure, Analyze, Improve and Control phases, including the statistics used in each phase. It is a 150-question, closed book, proctored exam with a 4 hour time limit, and IASSC may add up to 15 ungraded questions. You need a minimum score of 70% to be certified.

There are no prerequisites, so you do not need a Green Belt or a completed project before you sit the exam. An exam voucher costs $450 USD. You can test at a test center or through the PeopleCert Online Proctoring system, which runs 24/7, 365 days per year, and lets you schedule an exam to start within 1 hour.

If you do not pass, you cannot take a 2nd sitting within 2 weeks of the first, or a 3rd sitting within 3 months of the first. The certification is recognized perpetually, but “Current” status lasts 3 years. To renew it, you take a 75-question, 2-hour, closed book recertification exam that also needs 70% to pass.

Other organizations award Black Belt credentials under their own rules, so the details on this page apply only to IASSC. Fees and policies can change, so check them on the official IASSC website (iassc.org) before you buy a voucher.

Lean Six Sigma Black Belt Certification Exam at a Glance

What changed for Lean Six Sigma Black Belt Certification in 2026

• Oct 25, 2026: Delivery changed to Test centers or PeopleCert online proctoring (previously Test centers (Pearson VUE), PeopleCert online proctoring, or accredited providers).^[1]
• Oct 25, 2026: Validity changed to Recognized perpetually; "Current" status lasts 3 years (previously Recognized permanently; "Current" status lasts 3 years).^[3]

Lean Six Sigma Black Belt Certification content outline and where to practise each area

The content areas below are copied from the official Lean Six Sigma Black Belt Certification content outline published by IASSC. The right-hand column shows which of our practice sets covers it.

Worked examples: how to reason through Lean Six Sigma Black Belt Certification questions

These are practice questions written for this site, not questions from the real exam. Each explanation shows why the right answer is right and why the others are wrong.

Example 1

Question: The concept of 'Design for Six Sigma' (DFSS) is most closely associated with which methodology?

1. DMAIC
2. PDCA
3. DMADV
4. SIPOC

Answer: C. DMADV

Explanation:

C, DMADV, is correct. Design for Six Sigma is used when a product or process is being designed from scratch, or when an existing one is too broken to fix. DMADV stands for Define, Measure, Analyze, Design, Verify. It builds capability into the design from the start instead of fixing defects later.

• DMAIC improves a process that already exists. Its last phases are Improve and Control, not Design and Verify.
• PDCA is a general Plan-Do-Check-Act cycle for continuous improvement. It is not tied to designing new products.
• SIPOC is a scoping diagram (Suppliers, Inputs, Process, Outputs, Customers). It is a tool, not a methodology.

Rule to remember: to fix an existing process, use DMAIC. To design a new one, use DMADV, the DFSS method.

Example 2

Question: The GRR is typically 42% in a Measurement System Analysis activity, with Gage Variation and Part Variation each contributing equally. How would you respond?

1. Calibrate the equipment
2. Calibrate the equipment, check operator variation, and identify Part Variation.
3. Leave the GAGE. It is acceptable.
4. Calibrate the equipment and check operator variation

Answer: B. Calibrate the equipment, check operator variation, and identify Part Variation.

Explanation:

B is correct. A GRR of 42% means the measurement system accounts for far too much of the observed variation, so its data cannot be trusted yet. A full response deals with every source of variation: calibrate the equipment (repeatability), check how operators measure (reproducibility), and look into part variation so you know whether the gage can tell parts apart.

• A fixes only the equipment. It ignores operators and parts.
• C is wrong because a GRR this high is not acceptable.
• D covers equipment and operators but skips part variation, which the question says contributes equally.

Rule to remember: when gage R&R is high, investigate the equipment, the appraisers and the parts before you use the data for any decision.

Example 3

Question: Which of the following best describes a 'mistake-proofing' (poka-yoke) device?

1. A statistical control chart monitoring process output
2. A physical or electronic mechanism that prevents errors or makes them immediately obvious
3. A training program to reduce human error rates
4. A standard operating procedure checklist

Answer: B. A physical or electronic mechanism that prevents errors or makes them immediately obvious

Explanation:

B is correct. A poka-yoke is a physical or electronic mechanism built into the process. It either makes an error impossible or makes it obvious the moment it happens, such as a connector that only fits one way or a sensor that stops a machine when a part is missing.

• A, a control chart, is a statistical tool. It detects shifts in process output after they happen, but it does not physically prevent a mistake.
• C, training, depends on people remembering and paying attention. Poka-yoke is meant to remove that dependence.
• D, an SOP checklist, still relies on someone following it correctly.

Rule to remember: poka-yoke designs the error out of the process instead of asking people to avoid it.

How to use these practice tests

Start with a mixed set such as the assessment questions to find your weakest phases. Log every miss by DMAIC phase, not just your overall score.

Next, work through the phase sets in order: Define, Measure, Analyze, Improve and Control. Read every explanation, including for questions you guessed right. For statistics-heavy topics such as hypothesis testing, DOE and control charts, redo the working by hand or in a spreadsheet so you learn the method and not just the answer.

Alongside our sets, read the official IASSC exam outline on iassc.org, which defines what the exam covers. We wrote our questions for practice. They are not real exam items.

Before you book, do a full rehearsal. Combine the MCQ and prep sets until you have 150 questions, then answer them closed book within 4 hours. Aim to score clearly above 70% on questions you have not seen before. If a sitting goes badly, use the required gap of at least 2 weeks to rework your weakest phase.

Sources & last verified

1. IASSC — number of questions, time limit, exam fee, passing score (official source). “The IASSC Certified Lean Six Sigma Black Belt Exam™ is a 150 question, closed book, proctored exam” Verified Oct 25, 2026.
2. IASSC — retake policy (official source). “a 2nd sitting for the same examination may not be undertaken within two weeks of the first sitting.” Verified Oct 25, 2026 · source checked Oct 21, 2026.
3. IASSC — validity, renewal (official source). “Current status is granted to Candidates for a period of three (3) years” Verified Oct 25, 2026.
4. IASSC — testing window (official source). “24/7 365 days per year, Secure Online Delivery, Schedule your exam to be conducted within just 1 hour.” Verified Oct 25, 2026.
5. IASSC — other (official source). “define phase” Verified Oct 28, 2026.

How we verify: editorial & fact-checking policy. Report an error: contact us.