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Result
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This is the standard normal-approximation sample size for estimating a proportion. It is not an acceptance-sampling plan and does not replace AQL/OC-curve design.
How to use this calculator
What to enter
Enter or select the following as requested: Population size (0 = very large / unknown); Confidence level; Margin of error (%); Expected defect proportion (%). Follow the units, valid ranges, examples, and options displayed beside each field.
What the result means
The recommended sample size depends on the population size, confidence level, margin of error, and expected defect proportion. A larger confidence level or smaller margin of error generally requires more observations.
When to use it
Use this to analyze process quality or plan a quality-improvement study. Verify data collection and statistical assumptions before changing a process or reporting formal capability results.