an acceptable quality level (AQL) is defined in ISO 2859-1 as the ''quality level that is the worst tolerable''1. This means that the AQL is the limit of defective units that can be accepted in a continuing series of lots during random sampling quality inspections1. The AQL is usually expressed as a percentage or ratio of the number of defects compared to the total quantity1. The AQL helps to induce the supplier to maintain a process average at least as good as the specified limit, while providing an upper limit for the risk to the consumer of accepting the occasional poor lot1.

1: Acceptable Quality Level (AQL): Definition and How It Works - Investopedia