CQE Calculators

Five interactive calculators for the most-tested quantitative topics. Use them alongside the learn guides as you study — working through numbers yourself is the fastest way to make them stick.

The full set of free calculators, with more options, lives on Free quality tools.

1 — Process Capability (Cp, Cpk, Cpm)

Enter spec limits, process mean, and within-subgroup standard deviation. Pp/Ppk require long-term σ. Learn: Cp vs Cpk vs Cpm · Cpk vs Ppk

USL (upper spec)

LSL (lower spec)

Process mean (x̄)

Within-subgroup σ

Target T (for Cpm, optional)

Long-term σ (for Pp/Ppk, optional)

Results will appear here.

2 — Control Chart Limits

Select chart type and enter process parameters. Learn: X̄-R vs X̄-S · I-MR chart · Attribute charts

Chart type

Subgroup size n

Grand mean (x̄̄)

Average range R̄

Results will appear here.

3 — Acceptance Sampling (OC curve)

We don’t reproduce the sampling standard’s code-letter or Ac/Re tables; use the copy of the standard you’re allowed to bring to the exam. To see how any single sampling plan behaves, use the binomial OC curve calculator in the AQL guide: enter n, c and lot percent defective to get the probability of acceptance. Learn: switching rules.

4 — Normal Distribution (Z ↔ Probability)

Convert between Z-scores and tail probabilities. Learn: Normal distribution & z-table · Sigma level & DPMO

Enter either Z or probability — the calculator fills in the other.

Z-score

Tail probability P(X > Z)

Results will appear here.

5 — Exponential Reliability

Constant-failure-rate model. Learn: Bathtub curve & MTBF · Availability & maintainability

MTTF (mean time to failure, hours)

Mission time t (hours)

MTTR (for availability, optional)

Results will appear here.

Test yourself in 2 minutes

Try 5 free CQE practice questions on this topic. Every wrong answer comes with an explanation. No account needed.

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More: 5 Whys · 8D problem solving · AOQ & AOQL · APQP & PPAP · AQL sampling plans · Attribute agreement & kappa · Attribute control charts · Availability & maintainability · Benchmarking types · Binomial vs Poisson · Blocking & randomization · Calibration & traceability · Capability: non-normal · Chi-square test · Confidence intervals · Control chart selection · Control plan · CA effectiveness · Cost of quality · Cp vs Cpk vs Cpm · Cpk vs Ppk · CQE exam day tips · CQE study plan · CQE vs CQA vs CSSBB · Is the CQE worth it? · CUSUM & EWMA · Design reviews · Design V&V · Destructive testing · DFMEA vs PFMEA · Document control · Fault tree analysis · First article inspection · Fishbone diagram · FMEA: RPN vs AP · Full vs fractional factorial · Gage R&R · GD&T basics · Hazard vs risk vs harm · Hypothesis test selection · I-MR chart · Interaction plots · ISO 14971 · ISO 9001 clauses · Kaizen event planning · Kano model · Lean wastes (TIMWOODS) · Linear regression · Management review · MRB dispositions · MSA: bias, linearity & stability · NCR, CAPA & PA · Nonparametric tests · Normal distribution & z-table · One-way ANOVA · p-value explained · Pareto chart · PDCA vs DMAIC · Poka-yoke · QFD / House of Quality · Quality audits · Quality mgmt principles · Quality manual vs procedures · Quality plan vs control plan · Redundancy: parallel & standby · Reliability allocation · Bathtub curve & MTBF · Response surface methods · Risk-based thinking · Risk matrix vs FMEA · 7 mgmt & planning tools · Short-run SPC · Six Sigma certifications · Sigma level & DPMO · Six Sigma DMAIC · Supplier quality scorecards · Switching rules (sampling) · Taguchi loss function · Theory of constraints · Tolerance stackup · Traceability & lot control · Type I vs II error · Value stream mapping · Variables vs attributes · Weibull analysis · Western Electric rules · X-bar R vs X-bar S · CQE calculators · Study planner · Section quiz