AQL Sampling Calculator

This page evaluates acceptance sampling plans by computing their operating characteristic curve directly. Give it a lot size, a sample size and an accept number and it returns the exact chance of accepting a lot at any defect rate, the producer and consumer risks at the quality levels you name, the indifference quality and the worst average outgoing quality, with the curve drawn and tabulated. A second action runs the search the other way and finds the smallest sample and accept number meeting a pair of risks you choose. Every probability is the exact hypergeometric for sampling without replacement, not a binomial approximation, and this page does not reproduce the ANSI/ASQ Z1.4 code letter tables.

Calculator Type

Give the lot size, the sample size and the accept number, and this returns the exact operating characteristic curve for that plan along with both risks.

The number of items the accept or reject decision covers.
Accept the lot on this many defectives or fewer. The reject number is one more than this.
The defect rate you want almost always accepted. It is a limit on what is routinely tolerable, not a target and not a promise about any single lot.
The defect rate you want almost always rejected. Must be worse than the AQL.
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Choose the quality you want accepted and the quality you want rejected, with a risk on each. This searches for the smallest sample size and accept number that satisfies both.

The number of items the accept or reject decision covers.
The defect rate you want almost always accepted. It is a limit on what is routinely tolerable, not a target and not a promise about any single lot.
How often you are willing to reject a lot that was actually at the AQL. 5% is the usual choice.
The defect rate you want almost always rejected. Must be worse than the AQL.
How often you are willing to accept a lot that was as bad as the RQL. 10% is the usual choice.
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