What is AQL (Acceptable Quality Level)

The “AQL tables” are statistical tools at the disposal of buyers (for product inspections). They help determine two key elements:

How many samples should be inspected?
Where is the limit between acceptability and refusal, when it comes to defective products?
The need for an objective measurement of quality
In virtually every production batch, there will be defective products. It is true even after the manufacturer has checked each individual product and has repaired the defective ones.

Thus, in a supplier/buyer relationship, the supplier cannot be expected to deliver defect-free goods. However, the buyer wants to control the quality of purchased goods, since he does not want too many defects. But what does “too many” mean?

How to set the limit between acceptability and refusal in a way that can be agreed upon and measured?
Definition and application of ‘AQL’
The limit, as described above, is called the ‘AQL’. It stands for ‘Acceptance Quality Limit’, and is defined as the “quality level that is the worst tolerable” (ISO 2859 standard).

For example: “I want no more than 1.5% defective items in the whole order quantity” means the AQL is 1.5%.