AQL (Acceptable Quality Limit)

Acceptable Quality Limit (AQL) is a quality control procedure used to ensure that goods manufactured and received meet the agreed upon quality standards. It works by answering three questions:

  1. What percentage of defective items are acceptable?
  2. How many sample units should I inspect?
  3. How many defective items in the sample size are allowed?

AQL uses a statistical measurement to determine the maximum number of defective items that are considered acceptable in a sample size of the total order manufactured. AQL is specified by a level ranging from 0.065 to 6.5, which sets the ratio (percentage) of defect items found in a sample size to determine whether the entire order fails or passes inspection. The procedure is outlined by the International Organization for Standardization in ISO 2859-1.

AQL 2.5 Inspection Level S4

Carton defaults custom packaging and print to AQL 2.5 Inspection Level S4. We do this to balance costs / delays of additional inspection and providing an adequate number of samples for inspection.


Defects are classified into three levels: critical, major and minor. What makes something a minor, major, or critical defect? It depends! Each item and it's use case will define acceptable tolerances. This is something that should be discussed and negotiated with vendors.

Critical defects render product is unsafe or hazardous for the end user or that contravene mandatory regulations.

Major defects result in the product's failure, reducing its marketability, usability or saleability.

Minor defects do not affect the product's marketability or usability, but represent workmanship defects that make the product fall short of defined quality standards.

At Carton, each custom packaging and print item has an AQL policy defining the criteria for each defect.

Inspection Levels

AQL guidelines consists of two inspection levels: the General Inspection Levels and Special Inspection Levels.

General Inspection Levels are widely used and designed for routine quality control inspections of product with regular or consistent quality characteristics. There are three general inspection sub-levels: I, II, and III; General II being the most common for general consumer products.

Special Inspection Levels give you a smaller sample size than of the General Inspection Levels because it only applies to specific types of tests on your quality inspection checklist. Typically, Special Inspection Levels are used when testing is destructive, very technical, time-consuming, expensive, yields similar results across all items, or defects are of low concern. There are four special inspection levels: S1, S2, S3, and S4.

These levels and sub-levels specify different sample sizes and acceptance criteria based on the batch size and desired level of inspection stringency. Choosing the inspection level depends on factors such as item complexity, supplier and vendor relationship, risk level, budget, and general buyer analysis.

Industry Standard

AQL 2.5

AQL 2.5 is the industry standard applied to regular consumer goods, and by default on Carton. Acceptable under AQL 2.5 is as follows:

Critical00% of goods have critical defects
Major2.52.5% of goods have major defects
Minor4.04.0% of goods have minor defects

Despite industry standards, AQL 2.5 could mean that any defect (critical, major, or minor) of 2.5% is acceptable. Thus, it is worth clarifying the AQL policy with new suppliers and vendors.

AQL 2.5 is a general guideline and may vary depending on the specific requirements of each industry, product, and buyer. For example, tolerance and acceptance rates are stringent for the medical industry, aircraft products, and buyers like Apple in comparison to a run-of-the-mill fast food joint getting custom printed napkins.

GII with S-2

General Inspection Level II with Special Inspection Level 2 is the industry standard for sample sizes for regular consumer goods. GII achieves a wider coverage scope with relatively low costs. For a subset of costly and time-consuming testing, such as barcode scanning and sealing check, a S-2 sample size is used.


Updated on July 15, 2023

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