How to decide the limit between acceptability and refusal, based on the number of defects found? Before the inspection takes place, the customer should set the acceptance quality limit (AQL).

How to set the acceptance quality limit (AQL)?

The default AQL for most product inspections is:

  • 2.5% for major defects,
  • 4.0% for minor defects,
  • Critical defects are not allowed (0%).

Here is an example of a normal inspection with a sample of 200pcs:

An AQL of 4.0% means that the inspection is passed if 14 defects (or less) are found. But if 15 defects or more are found, the inspection is failed.


ISO 2859 definition for “acceptance quality limit”

“Quality level that is the worst [acceptable]”
“If the number of [defects] found in the sample is equal to or less than the acceptance number, the lot shall be considered acceptable. If the number of nonconforming items is equal to or greater than the rejection number, the lot shall be considered not acceptable.”


Set your AQL easily with our calculator

We have an easy-to-use AQL calculator which makes it simple to get the sample size and permissible defects for your quality inspectors.


For more in-depth information about AQL read here:

AQL statistical tables

Description of the AQL

Bookmark the permalink.

Comments are closed.