How an AQL inspection works on a babywear order

"AQL 2.5" appears in almost every apparel purchase order and is understood by almost nobody who writes it. It is worth ten minutes, because it determines whether a lot ships or is held.

What AQL is

Acceptable Quality Level is a statistical sampling scheme. Rather than inspecting every garment — which is slow and still does not catch everything — you inspect a calculated sample drawn from the lot and decide from the defect count in that sample whether the whole lot is releasable.

It is defined in ISO 2859-1 and its equivalents. The key word is statistical: an accepted lot is not a perfect lot. It is a lot that plausibly meets the standard.

The sample size comes from the lot size

The sample size is set by the lot size and the inspection level, not by the AQL. For a normal single-sampling plan at inspection level II, the general shape is:

Note what this means in practice: a 10,000-piece lot is judged on 200 garments. That is the deal you are signing up to when you specify AQL, and it is why inline and end-line inspection matter as much as the final one.

The three defect classes

• Critical. A defect that makes the product unsafe or illegal to sell — a broken needle fragment, a sharp point, a fastener that releases under load, a missing required label. The usual acceptance number is zero. A single critical defect fails the lot.
• Major. A defect that makes the garment unsellable or that a customer would return — a hole, a broken seam, a significant measurement deviation, a wrong colour trim.
• Minor. A defect that a customer would notice but probably accept — a loose thread, slight puckering, minor shade variation. Usually the largest allowed number.

Why the classification matters more than the level

Two orders can both say "AQL 2.5" and mean completely different things, depending on what each side classifies as major. A 3 mm measurement deviation might be major to one buyer and minor to another. If the classification is not agreed in writing before production, the inspection result becomes an argument rather than a decision.

So: agree the defect classification alongside the AQL number. Better still, attach photographs of what you consider major to the purchase order.

What to specify in the order

• The AQL level for each defect class, and the classification itself.
• Measurement tolerances per measurement point, not a single blanket figure.
• Whether critical defects have a zero acceptance number.
• Who inspects — the factory, a named third party, or your own team.
• Where the inspection happens and whether the lot is held for it.
• What happens on a fail: rework, remake, or a second sample.

Baby-specific checks that sit outside AQL

Some controls are not statistical and should not be sampled:

• Needle detection on every garment, not a sample. This is a safety control with a zero tolerance, so every piece passes through the detector.
• Small-parts security — pull testing of snaps, buttons and applied trims against the applicable standard for the age group.
• Sharp points and edges on zips, snap covers and trim ends.
• Label presence and content — fibre content, care instructions, origin, and any required tracking mark. A missing label is a compliance failure, not a minor defect.

The practical summary

Specify the AQL level and the defect classification. Put needle detection outside the sampling scheme, because it is a safety control. Agree what happens on a fail before the lot exists. And remember that a passed AQL inspection means the lot is releasable, not that it is flawless.