AQL (Acceptable Quality Limit)
AQL is the internationally standardized sampling method (ISO 2859-1 / ANSI Z1.4) that defines the maximum percentage of defective units a buyer will accept in a press-on nail production lot, using statistical sample sizes instead of checking every piece.
Trend context
Key fact
Under the industry-standard AQL 2.5 (ISO 2859-1), a 10,000-unit lot is inspected via a roughly 200-unit random sample, and press-on nail buyers typically contract AQL 2.5 for major defects and 4.0 for minor ones (Tetra Inspection; Xianxing Beauty sourcing guide, 2026).