AQL Sampling Plan Calculator

What it does

Acceptance sampling decides whether to accept a lot by inspecting a sample instead of every item. Enter the lot size, the inspection level and the type of inspection (normal, tightened or reduced), give each defect class its own AQL, and the calculator gives the sample size, the acceptance number Ac and the rejection number Re for each class. Enter what you found and it gives the decision for each class and for the lot, with notes for the cases that need attention.

AQL (acceptance quality limit) is the worst quality level that is tolerable as a process average over a continuing series of lots. It is not a promise that every accepted lot is that good.

Method

The plans come from the single sampling tables of the current edition of the standard, ISO 2859-1:2026, checked cell by cell against it, including the cases where a defect class has to use another sample size. The switching rules between normal, tightened, reduced and skip-lot inspection are listed on the page under the results.

Worked example

The data behind “Try an example”: a lot of 1,000 items, general inspection level II, normal inspection.

The Critical class needs a larger sample than the other two, which the calculator flags. Minor defects reached the rejection number, so the lot is not accepted even though Critical and Major passed.