Practice tools for quality and compliance professionals
A small studio making study tools for people who work in quality: exam practice that explains every wrong answer, and free calculators for the math you use on the job.
Exam prep
CQE Available
Certified Quality Engineer practice: written questions, fresh-number calculation problems, a held-back Final Exam and error-pattern tracking.
See CQE practice →Six Sigma Black Belt Free questions
CSSBB study guides for all 9 sections of the 2022 Body of Knowledge, a free diagnostic, and DMAIC tollgate checklists. The 25 diagnostic questions are free in the CSSBB Quest app now; checkout for the full practice bank (306 original questions, plus unlimited fresh calculation and chart problems with new numbers every time) is opening soon.
See Black Belt study →Open CSSBB Quest →
Six Sigma Green Belt Free questions
CSSGB study guides for all 6 sections of the 2022 Body of Knowledge, a formula sheet and a free diagnostic. The 20 diagnostic questions are free in the CSSGB Quest app now; checkout for the full practice bank (300 original questions, plus unlimited fresh calculation and chart problems with new numbers every time) is opening soon.
See Green Belt study →Open CSSGB Quest →
Not sure which certification?
Compare CQE, Green Belt and Black Belt by role, experience required and what each exam covers.
Find your certification →Free tools
Process capability calculator
Have the mean and σ already? Get Cp, Cpk, Pp, Ppk, centering k and expected PPM on each side, with a live curve.
Open →Control chart constants
A₂, A₃, d₂, d₃, c₄, D₃, D₄, B₃, B₄ for n = 2–25, plus an X̄-R / X̄-S limits calculator.
Open →Cpk and Ppk from raw data
Paste raw data and spec limits. Estimates within and overall σ for you, with the sigma method shown.
Open →Control chart picker
Three questions to the right chart (I-MR, X̄-R, X̄-S, p, np, c, u), with the reason.
Open →Sample size calculator
Sample size for a mean, a proportion, or a test with chosen alpha and power.
Open →Guides
Cpk vs Ppk
Choosing a control chart
Type I vs Type II error
Gage R&R explained
FMEA: RPN vs Action Priority
AQL and acceptance sampling
Full vs fractional factorial DOE
Which hypothesis test to use
Bathtub curve and MTBF
Free printable CQE formula sheet · How we check every question
Try 5 free practice questions with an explanation for every wrong answer.
Take the free CQE quiz