Defect Rate

Defect Rate is a core indicator in foreign trade quality control, referring to the percentage of defective items in a batch relative to the total inspected quantity, commonly used to measure a supplier's production quality level. It is calculated as: Defect Rate = (Number of Defective Items / Total Inspected Quantity) × 100%. In foreign trade contracts, buyers and sellers often agree on an Acceptable Quality Level (AQL) and set a maximum allowable defect rate accordingly, serving as the basis for inspection and claims. Use cases include: Pre-Shipment Inspection (PSI), factory audits, quality complaint handling, etc. Note: Defect Rate is often used interchangeably with 'nonconforming rate,' but strictly speaking, defect rate can refer to the number of defects per unit product (e.g., DPU), while nonconforming rate refers to the proportion of nonconforming items; moreover, the definition of defects (critical, major, minor) and sampling standards (e.g., ISO 2859) must be clarified. Unlike 'return rate,' defect rate focuses on production-end quality, while return rate reflects overall market-end performance. Foreign trade practitioners should monitor defect rate trends to avoid rejection or claims due to batch exceedance.