AQL stands for Acceptable Quality Limit — the internationally recognised sampling standard used in apparel quality control. Understanding AQL helps you set meaningful quality standards in your purchase orders and interpret QC inspection reports when your goods are produced.
What is AQL?
AQL defines the maximum percentage of defective units considered acceptable in a production batch. An AQL of 2.5 means that if 2.5% or fewer units in the batch are defective, the batch passes inspection. If more than 2.5% are defective, the batch fails.
AQL inspection works by sampling a statistically defined number of units from the full production batch and inspecting them for defects. The sample size and acceptance/rejection numbers are defined by international standard ISO 2859-1 — a table that has been the global quality inspection standard for decades.
AQL Levels Used in Apparel
AQL values range from 0.065 (extremely tight, used for critical components) to 6.5 (very permissive). The most commonly used AQL levels in apparel manufacturing are:
- AQL 1.0 — tight standard. Used for critical defects or premium products. Accepts very few defective units.
- AQL 2.5 — the most common standard in apparel. Used by the majority of UK, US and EU retail buyers for major defects.
- AQL 4.0 — permissive standard. Used for minor defects or lower-price-point programmes.
Most professional buyers specify AQL 2.5 for major defects and AQL 4.0 for minor defects. Critical defects (safety issues, wrong product, missing labels) are typically specified at AQL 0 — zero tolerance.
Major vs Minor vs Critical Defects
- Critical defects — safety hazards, legal non-compliance, completely wrong product. AQL 0 — any critical defect fails the inspection.
- Major defects — defects that a consumer would likely reject. Broken seams, significant colour deviation, wrong size label, missing label, significant measurement deviation. AQL 2.5 is standard.
- Minor defects — cosmetic imperfections that do not affect function. Slight thread pull, minor print registration, minor measurement tolerance. AQL 4.0 is standard.
How AQL Sampling Works in Practice
For an order of 3,200 units at AQL 2.5 with General Inspection Level II (the standard for apparel):
- Sample size: 125 units are randomly selected from the production batch
- Acceptance number: if 7 or fewer major defects are found in 125 units, the batch passes
- Rejection number: if 8 or more major defects are found, the batch fails
Always specify AQL in your purchase order. A manufacturer who does not know what AQL means or cannot conduct AQL inspections is not operating to professional quality standards.
Who Conducts AQL Inspections?
AQL inspections can be conducted by: the manufacturer's in-house QC team, a third-party inspection company (SGS, Bureau Veritas, Intertek are common choices for apparel), or your own QC staff if you have them in the production region. Third-party inspection provides the highest level of objectivity and is standard practice for orders above a certain value.
What to Specify in Your Purchase Order
Include in every purchase order: AQL level for critical defects (typically 0), AQL level for major defects (typically 2.5), AQL level for minor defects (typically 4.0), inspection stage (in-line, pre-shipment or both), who conducts the inspection (manufacturer in-house or third party), and the right to reject the batch if inspection fails.