Qhubio

    Process Capability & Performance Calculator

    Turn Cp, Cpk, Pp and Ppk into an engineering decision

    Calculate capability and performance indices, then generate structured engineering judgement, business impact and ready-to-send communication.

    No installation. No sales call. Immediate browser access.

    Capability numbers are easy. Engineering decisions are harder.

    See the complete output of one real capability study

    Every number, judgement and email below is the actual product output of a single saved Qhubio study — not a marketing mock-up. The same study is available as a full downloadable PDF report.

    Real Qhubio study · snapshot 2026-08-15

    Disposable Phase B precision acceptance

    Individuals / Moving Range · n = 40 · LSL 9.9850 / USL 10.0150 · Target 10.0000

    Download the full example report (PDF)

    Cp

    0.392

    Within-process potential

    Cpk

    0.387

    Nearest specification

    Pp

    0.504

    Overall performance

    Ppk

    0.499

    Overall, nearest specification

    Observed nonconformance

    15.0%

    6 of 40 measurements (3 above USL, 3 below LSL)

    Mean

    10.00016

    Within sigma 0.01277 · overall sigma 0.00992

    Expected normal-model PPM

    130420

    Model yield 86.96%

    Process Distribution

    Process Distribution with 40 observations from 9.978 to 10.022, freedman-diaconis binning, and 6 observations outside specification. Fitted curves are diagnostic overlays for the individual/I-MR method; they do not prove normality or statistical control.

    Individuals Chart

    Individuals Chart with 40 observations and 0 screening signals.

    No I-MR screening violation was detected in the supplied sequence. This does not prove statistical control. No strong normality-screening signal was detected. This is not proof of normality.

    Release decision

    Do not release

    Do not release. The process does not have sufficient inherent capability to meet the internal screening benchmark Cpk >= 1.33. 6 observed measurements exceed the specification limits (3 above USL and 3 below LSL). Verify the nonconforming observation and measurement system, reduce sources of variation then confirm capability with a representative time-ordered study before release.

    Decision confidence: High · Diagnostic confidence: Moderate

    Primary diagnosis

    Excessive variation

    Release risk

    Release would accept a study that does not demonstrate the applicable capability requirement and contains 6 observed measurements outside specification (3 above USL and 3 below LSL).

    Prioritized investigation plan

    ImmediateContain or trace the affected output.

    An observed measurement is outside specification (3 above USL and 3 below LSL) and the internal screening capability benchmark 1.33 is not demonstrated.

    HighVerify the observed upper-specification failure: repeat the measurement and confirm traceability before disposition.

    maximum 10.022 exceeds the USL 10.015. No measurement system is recorded for this study.

    HighRecord and verify measurement-system adequacy (MSA / Gage R&R) before a release decision.

    No measurement system is recorded, so measurement error cannot be separated from process variation.

    HighReduce within-process variation.

    Cp 0.392 is below the internal screening benchmark 1.33, so even perfect recentring is insufficient at the current within-process spread.

    NormalCollect a representative time-ordered confirmation study after corrective action and release only once the applicable requirement is demonstrated.

    40 measurements were supplied. A confirmation study is required to demonstrate the corrected state.

    EvidenceResultInterpretationDecision impact
    Capability benchmarkCpk >= 1.33 (internal screening benchmark)No customer requirement was recorded for this studyScreening only - not a customer release gate
    Cp0.392Potential short-term capability if centered; below the internal benchmark Cpk threshold 1.33, therefore perfect centering alone cannot satisfy itVariation / corrective action
    Cpk0.387Capability relative to nearest specificationRelease decision
    CPU / CPL0.387 / 0.396Two-sided capability contributionCentering corrective action
    Pp / Ppk0.504 / 0.499Overall performance evidencePerformance confirmation
    Observed defects3 above USL and 3 below LSL / 40 totalObserved nonconforming output in the supplied sampleProduct / customer risk
    StabilityNo implemented I-MR signal detectedNo screening signal detected; this does not prove statistical controlDiagnostic confidence
    NormalityA² 0.038 / p 1.000No strong normality-screening signal detected; this does not prove normalityModel-assumption screening - no current blocking signal
    Business ImpactUser-confirmed traceable production rate$25,780.00; dominant driver ScrapImprovement prioritization

    Evidence gaps

    • Measurement system not recorded; MSA / Gage R&R evidence is missing.
    • Sampling representativeness is not independently proven by the supplied measurements.
    • No customer capability requirement is recorded for this study.

    What would change the decision

    • Confirm and disposition the observed out-of-specification measurement and the affected material.
    • Verify measurement-system adequacy appropriate to the characteristic.
    • Reduce within-process variation sufficiently that a representative confirmation study meets the internal screening benchmark Cpk >= 1.33.
    • Demonstrate the applicable capability requirement on a representative time-ordered confirmation study with no unresolved stability-screening concern.

    Annual COPQ

    $25,780.00

    User-confirmed traceable production rate

    Target scenario at Cpk 1.33

    $11,048.85

    Centered two-sided planning scenario

    Potential scenario savings

    $14,731.15

    Dominant cost driver: Scrap

    Evidence classificationProduction estimate
    Defect-rate basisTraceable production rate — 2%
    Sourcequality-system · DISP-PHASE-B-20260815
    Annual production100,000
    Scrap$9,600.00
    Rework$2,100.00
    Containment$2,000.00
    Sorting$5,000.00
    Inspection$1,000.00
    Complaints$1,000.00
    Returns$80.00
    Downtime$5,000.00

    The target scenario is a planning calculation, not a forecast, and does not demonstrate that the target Cpk will be achieved.

    Management summary

    Subject: Decision required: Process capability risk for Disposable Phase B precision acceptance

    Hello [Name]

Study: Disposable Phase B precision acceptance.
Traceability context is incomplete.
Decision: Do not release.
Key risk: Release would accept a study that does not demonstrate the applicable capability requirement and contains 6 observed measurements outside specification (3 above USL and 3 below LSL).
Production estimate based on a user-confirmed traceable production rate. Defect-rate basis: 2 %. Source: quality-system record DISP-PHASE-B-20260815. Qhubio records the source and reference but does not independently validate the production record. Annual COPQ: $25,780.00 USD. Projected COPQ at target Cpk 1.33: $11,048.85. Estimated annual savings: $14,731.15. Dominant cost driver: Scrap.
Requested decision: approve the proposed release/containment direction and assign an owner.
Required owner/action/date: [Owner] / [Action] / [Date].
Next step: [Next step].

Regards,
[Your name]

    Technical communication

    Subject: Action required: Capability investigation for Disposable Phase B precision acceptance

    Hello team,

Study: Disposable Phase B precision acceptance.
Part: not recorded | Machine: not recorded | Lot: not recorded.
Measurement system: not recorded.
Cpk 0.387; Ppk 0.499; observed defects 6.
Triggered rule: No implemented screening signal detected.
Diagnosis: Excessive variation.
Containment / release direction: Do not release.

Operational financial priority:
Production-evidence estimate.
Dominant cost driver: Scrap.
Current annual exposure: $25,780.00 USD.
Target-state opportunity: $14,731.15 at Cpk 1.33.
Action: prioritize the controls and corrective work linked to Scrap.

1. Contain or trace the affected output.
2. Verify the observed upper-specification failure: repeat the measurement and confirm traceability before disposition.
3. Record and verify measurement-system adequacy (MSA / Gage R&R) before a release decision.
4. Reduce within-process variation.
5. Collect a representative time-ordered confirmation study after corrective action and release only once the applicable requirement is demonstrated.

Owner/date: [Owner] / [Date].
Recalculate after the required representative time-ordered sample and stated evidence gaps are closed.

Regards,
[Your name]

    Placeholders such as [Owner] and [Date] remain editable before sending.

    Values are a frozen snapshot of one real saved study. No AI request is made to display this example.

    Download the example report

    The calculation is free. The decision support is paid.

    Use the calculator to obtain Cp, Cpk, Pp and Ppk. Upgrade only when you need structured interpretation, business context and communication you can use immediately.

    Free calculation

    What the calculator gives you without payment.

    • Cp, Cpk, Pp and Ppk calculation
    • Statistical result
    • Capability and performance visualization
    • Numerical output
    • Manual interpretation and communication

    Paid decision support

    What the paid layer adds on top of the same calculation.

    • Engineering interpretation
    • Capability-risk explanation
    • Business and operational impact
    • Executive summary for management
    • Detailed technical communication
    • Ready-to-send email preparation

    The paid layer does not replace the calculation. It converts the statistical output into an actionable decision.

    Choose your access

    Both options unlock the same decision-support outputs. Choose whether you need one individual analysis or recurring access.

    Save the current Process Capability study before purchasing premium access. Premium Engineering Judgement and Business Impact are linked to a saved Study ID.

    One-Time Pass

    $0.99one-time

    Best for an occasional capability or performance study.

    Unlock Engineering Judgement, Business Impact and Email Communication for one individual analysis.

    • Engineering Judgement

      Structured interpretation of capability, centering, variation and process risk.

    • Business Impact

      Practical implications for scrap, rework, delivery, customer exposure and operational decisions.

    • Email Communication

      • Executive summary for management
      • Detailed technical explanation for quality and engineering teams

    A One-Time Pass is bound to one saved Capability Study. .

    Best for recurring use

    Monthly Access

    $4.99per month

    Best for engineers who perform capability or performance studies regularly.

    Use paid decision support across all your analyses while the subscription is active.

    • Engineering Judgement

      Structured interpretation of capability, centering, variation and process risk.

    • Business Impact

      Practical implications for scrap, rework, delivery, customer exposure and operational decisions.

    • Email Communication

      • Executive summary for management
      • Detailed technical explanation for quality and engineering teams

    Monthly Access must be started from a saved Capability Study. .

    Secure Stripe checkout · Cancel monthly access anytime · No installation

    Frequently asked questions

    Choose the access model that fits your workload

    Use the One-Time Pass for an individual analysis or Monthly Access for recurring capability studies. Both unlock the same decision-support outputs.

    Save the current Process Capability study before purchasing premium access.

    Secure Stripe checkout · Cancel monthly access anytime · No installation