The acceptance number is the maximum number of defects or defective units in the sample that will permit acceptance lot or batch.

Acceptance Sampling is used to decide whether to accept or reject a production lot. After selecting a sampling from a production lot, we inspect the units, we count how many defects are found among this sampling and we use the result (number of defects found versus maximum number of defects allowed) to decide whether or not to accept or reject the lot.

The AQL values are defined as percent nonconforming or defects or nonconformities per hundred units.