VYRCO / Quality and measurement

p chart for nonconforming units

Compare sample proportions with limits that adapt to different sample sizes.

Free · no accountv1.0 · 2026-10-10Private inputs in your browser

p chart for nonconforming units

VYRCO · v1.0 · https://vyrco.com/en/tools/p-chart/

Input data

Numbers: use a decimal point or comma, without thousands separators. Complete fields unless marked optional.

Preparing the tool…

Your inputs are processed here and are not sent to VYRCO. There is no autosave: download your project before closing or switching languages. Opening JSON reads a local file; it does not upload it. CSV includes inputs and results. For PDF, use Print / PDF and select Save as PDF.

How to use it

Record nonconforming units; count each unit at most once.
Keep each sample size and chronological order.
Review signals and assumptions; retain product acceptance criteria separately.

Fictional example

Fictional example: 12 nonconforming units among 400 inspected; center line 3%.

Method

p̄=Σnonconforming/Σinspected. For each sample: p=d/n; limits=p̄±3√[p̄(1−p̄)/n], bounded to [0,1]. A point signal occurs when p is strictly outside.

Scope and limitations

Binomial model with independent units and comparable probability. Does not count multiple defects per part. Exploratory limits; no run rules. Small expected counts weaken the approximation and do not justify automatic decisions.

Sources and review

NIST · Proportions control charts
Accessed: 2026-10-10

Tool v1.0 · Reviewed 2026-10-10. To report an error, include tool, version, units and a non-confidential example.

info@vyrco.com

p chart for nonconforming units

p chart for nonconforming units

Input data

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