What Is Acceptable Quality Level (AQL)?
The acceptable quality limit (AQL) is a measure applied to products and defined in ISO 2859-1 as the “quality level that is the worst tolerable.” The AQL tells you how many defective components are considered acceptable during random sampling quality inspections. It is usually expressed as a percentage or ratio of the number of defects compared to the total quantity.
How Acceptable Quality Level (AQL) Works
Goods in a sample are tested at random, and if the number of defective items is below the predetermined amount, that product is said to meet the acceptable quality level (AQL). If the acceptable quality level (AQL) is not reached for a particular sampling of goods, manufacturers will review the various parameters in the production process to determine the areas causing the defects.
As an example, consider an AQL of 1% on a production run. This percentage means that no more than 1% of the batch can be defective. If a production run is composed of 1,000 products, only 10 products can be defective. If 11 products are defective, the entire batch is scrapped. This figure of 11 or more defective products is known as the rejectable quality limit (RQL).
The AQL is an important statistic for companies seeking a Six Sigma level of quality control 503, which is a quality-control methodology developed in 1986 by Motorola, Inc. AQL is also known as the acceptable quality limit.
The AQL of a product can vary from industry to industry. For example, medical products are more likely to have more stringent AQL because defective products can result in health risks.
In contrast, a product with benign side-effects from a possible defect may have a less strict AQL, such as the remote control for a TV. Companies have to weigh the added cost associated with the stringent testing and potentially higher spoilage due to a lower defect acceptance with the potential cost of a product recall.
Customers would, of course, prefer zero-defect products or services—the ideal acceptable quality level. However, sellers and customers usually try to arrive and set acceptable quality limits based on factors typically related to business, financial, and safety concerns.