AQL Inspection Levels Explained

Given a total order quantity, an AQL table tells you the sample size to inspect (e.g. inspecting 125 units from a 3,000-unit order) and the maximum number of defects allowed in that sample at each severity level before the batch fails.

Defects are generally split into three tiers: critical (renders the product unsafe or unusable, zero tolerance), major (affects function or saleability), and minor (cosmetic issues unlikely to affect use). Each tier has its own acceptance threshold.

A commonly used general standard is AQL 2.5 for major defects and AQL 4.0 for minor defects, though this varies by product category and risk tolerance. Products with safety implications (electronics, children's items, anything with a choking hazard) often warrant a tighter AQL and closer scrutiny of the critical-defect category, which typically has zero acceptable occurrences regardless of the general level chosen.

The right level is a commercial decision balancing inspection cost, product risk and your tolerance for returns, it isn't a single fixed rule that applies to every product.

AQL levels and defect definitions should be agreed with the supplier in writing before production starts, ideally as part of the purchase order, not decided on the day of inspection. This avoids disputes about what counts as a 'defect' versus a cosmetic variation.

A pre-shipment inspection against an agreed AQL, carried out by an independent party rather than the factory itself, is standard practice for import orders of meaningful volume and gives you a documented basis to hold back payment or dispatch if a batch fails.