What AQL 2.5 Actually Means for Your Inspection Protocol

AQL 2.5 means that in a given production lot, a maximum of 2.5% defective units is considered acceptable. But the application is more nuanced than the number suggests.

How Sampling Works

AQL inspection uses statistical sampling tables (ISO 2859). For a lot of 1,200 units with AQL 2.5, the inspector typically samples 125 units and accepts the lot if 7 or fewer defects are found.

Defect Classification

Not all defects are equal. Critical defects (safety failures) typically use AQL 0 — zero tolerance. Major defects (functional failures) use AQL 2.5. Minor defects (cosmetic issues) may use AQL 4.0.

Third-Party vs Factory Inspection

For institutional orders over 2,000 units, we recommend third-party pre-shipment inspection at AQL 2.5 Major / 4.0 Minor as a minimum protocol. This protects the buyer and gives the factory clear pass/fail criteria.