What Does 2.5 AQL Mean in Inspection System?

From the previous article “What is AQL? How to Read and Use AQL Chart?” we knew the definition and reading system of AQL. We also were familiar with a table named AQL table. In that table, there were three levels of AQL (2.5, 4 and 6.5). Among them, 2.5 is the most common criteria for the apparel industry. Sometimes the buyer uses these AQL levels as the quality performance of a factory. 2.5 AQL means the quality performance is high and 6.5 means relatively low. Now the question is what does the AQL 2.5 mean in the inspection system? In this article, I will discuss to make answer this question.

We know that AQL means Acceptable Quality Level. Generally, there is three levels of AQL. Each level holds different values for accepting or rejecting the lot/batch. 2.5 is one of the levels of AQL.

Let’s look at the below AQL table. There is a column named 2.5 just below the Acceptable Quality Level. This column has two sub-column named Ac (Accept) and Re (Reject) which represents the values of acceptance and rejection for the specific lot and sample size.

Figure: AQL Table/Chart

For example, we have a shipment of 120 pieces. If we want to do the 2.5 AQL inspection. First of all, we need to specify the lot size for that quantity. From the table we find that the lot size is 91 – 150 named code – F. So the sample size will be 20 pieces and have to pick 20 pieces to check.

Now, look at the 2.5 AQL column to see the acceptance and rejection criteria. After checking if we find 1 piece defective items this lot will accept for shipment and if we find 2 or more defective items this lot will reject for shipment.

For more easy access to 2.5 AQL table, other level column has been removed for below table.

Figure: 2.5 AQL Table/Chart