When a buyer asks for a “final inspection at AQL 2.5”, they are asking for a statistical sampling inspection: a set number of garments is pulled at random from the finished order, inspected, and the whole lot passes or fails based on how many defects are found.
AQL stands for Acceptance Quality Limit (often called Acceptable Quality Level). It is the worst average defect rate that the sampling plan will routinely accept. AQL does not mean the order contains 2.5% defective garments; it describes how strict the sampling plan is.
The standard behind it
Most apparel inspections use the sampling tables in ISO 2859-1 (equivalent to ANSI/ASQ Z1.4). To use them you need three things:
- Lot size: the number of pieces in the shipment or order being inspected.
- Inspection level: usually General Inspection Level II, the default for apparel.
- AQL values: one for each defect class.
Defect classes
Inspections normally classify defects into three groups, each with its own AQL:
- Critical: a defect that could harm the user or break the law, such as a broken needle left in the garment or a missing mandatory label. Most buyers set this to zero tolerance.
- Major: a defect likely to cause a return, such as an open seam, a wrong measurement beyond tolerance, a visible stain or a shade difference within a garment.
- Minor: a defect unlikely to cause a return, such as a short loose thread or slight uneven stitching on an inside seam.
A common apparel specification is 0 critical, 2.5 major, 4.0 minor. Premium brands sometimes tighten major defects to 1.5.
Reading the tables: an example
Take an order of 3,000 shirts inspected at General Inspection Level II:
| Lot size | Code letter | Sample size | AQL 2.5 (major) accept / reject | AQL 4.0 (minor) accept / reject |
|---|---|---|---|---|
| 501–1,200 | J | 80 | 5 / 6 | 7 / 8 |
| 1,201–3,200 | K | 125 | 7 / 8 | 10 / 11 |
| 3,201–10,000 | L | 200 | 10 / 11 | 14 / 15 |
For 3,000 shirts, the inspector pulls 125 pieces at random. If 7 or fewer have major defects, majors pass; at 8 or more, the lot fails. Minor defects are counted separately against 10 / 11. A single critical defect fails the lot when critical AQL is zero.
What AQL does not do
- It does not replace in-line inspection. By the time a final inspection fails, the goods are made; finding the problem at the sewing station is cheaper for everyone.
- It does not check what isn’t on the checklist. Measurements, fabric shade, labels, packing and carton counts should all be on the inspection checklist, agreed in advance.
- It is not a guarantee about every garment. It is a statistical decision about the lot.
How to use AQL as a buyer
Agree the AQL levels, defect definitions and checklist before production starts, and attach them to the purchase order. Decide who inspects: the factory’s own QC, your team, or a third-party agency. Our quality control page describes the checks made at each stage of production before a final inspection takes place.