What does the inspection standard AQL 2.5 mean?

AQL stands for Acceptance Quality Limit, which refers to the maximum number of defects allowed in a batch of products agreed upon by the buyer and seller. Importers can set different levels of AQL standards, including fatal defects, major defects and minor defects.

Most Asian exporters are familiar with this term in trade, especially the AQL 2.5 standard is widely used in purchase orders and quality inspections. But what does AQL 2.5 stand for? How is it calculated? This guide will fully explain the AQL 2.5 standard and guide you on how to read the AQL sampling table.

What is AQL?

When importing goods from suppliers, it is crucial to ensure that product quality meets expectations and establish an efficient quality assurance mechanism.

AQL sampling is a practical and efficient quality inspection method that can reduce risks when ordering finished products and help companies identify problems before formal delivery.

If you want to know the specific application of AQL in quality inspection and how to determine the sample size through the AQL sampling table, you can click the link below to learn more.

AQL Defect Types

Three types of quality defect standards are usually used in the AQL sampling method:

Fatal flaw (0% tolerance)

Major defects (2.5% tolerance)

Minor defects (4.0% tolerance)

Fatal defects (0%) are completely unacceptable because they may cause injury to the user; major defects (2.5%) refer to products that the end user considers to be substandard; minor defects (4%) do not meet specifications but are still likely to be accepted by most buyers.

Usually, the acceptable level of defects is determined by negotiation between the buyer and the seller, depending on their risk tolerance. Products with higher health risks will have a lower AQL threshold. Once the AQL standard is determined, it will run through the quality inspection process as a basis for determining whether various defects in the order are qualified.

What does AQL 2.5 mean?

AQL 2.5 means that the acceptable proportion of major defective products in the entire batch of goods is 2.5%. If the batch defect rate exceeds 2.5%, it is considered to have failed to meet the agreed quality requirements. The AQL 2.5 standard is commonly used in the clothing industry, Chinese manufacturers and other fields.

What is an AQL sampling table?

The AQL sampling chart is a tool used to determine the inspection sample size and the acceptable number of defects. The chart also provides more options, including inspection levels and special case criteria.

The most commonly used standard is the AQL table1, which is an important tool for performing quality control inspections. This table simplifies the information communication between the buyer, manufacturer and quality inspection service provider, and the three parties can jointly agree on the inspection standards based on this table.

Table 1: Sample size code letters

How to read the AQL sampling table (taking AQL 2.5 as an example)

Reading the AQL 2.5 sampling table is relatively simple:

The table below shows the single sampling plan for routine inspection. The "√" in the table indicates the number of qualified products, and the "×" indicates the number of unqualified products. If the sample size pointed by the arrow is equal to or exceeds the batch size, full inspection or piece-by-piece inspection is required.

Table 2: Single sampling plans for Normal Inspection

The Importance of AQL in Quality Inspection

AQL is the core tool for sampling inspection. The quality inspection team uses AQL standards to ensure that the sample size is correct and record the number of defects that may lead to batch rejection. The standard specifies the sample size to be inspected and the rejection threshold.

It is time-consuming and labor-intensive to inspect large quantities of products piece by piece, but the use of methods such as AQL 2.5 can significantly improve efficiency. Therefore, when it is necessary to quickly determine whether the entire batch of products meets the quality requirements, AQL is the preferred option. However, it should be noted that if the purchase volume is small, the company can conduct a full inspection by itself; when the order volume is large, piece-by-piece inspection will face time and cost pressures.

AQL 2.5 is a reliable model that has been proven for many years, but it should be noted that AQL inspection cannot guarantee zero defects (minor defects may not be detected). Its core value is that it allows companies to set an acceptable defect ratio based on their risk tolerance, thus providing an important basis for supply chain management and product quality assessment.

After completing the AQL inspection, the quality inspection agency will issue a shipping certificate to clarify whether the batch has passed the inspection. The inspector will also perform a pre-shipment inspection before production begins and attach the inspection report as a shipping document.