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China sourcing guide

What AQL means and when it is useful

AQL is a statistical sampling framework used to select an inspection sample and compare observed defect counts with agreed acceptance limits; it does not mean that an accepted shipment contains no defects.

The finished lot quantity and any rules for separating different models, colors, sizes or production batches.The product specification, approved sample and measurable workmanship or functional requirements.The defect definitions and classification of critical, major and minor nonconformities.The intended inspection level, acceptance limits and any tests that must be performed outside the statistical sample.

What this topic means

AQL is a statistical sampling framework used to select an inspection sample and compare observed defect counts with agreed acceptance limits; it does not mean that an accepted shipment contains no defects.

  • The lot size and selected inspection level are used to determine a sample size under the chosen sampling standard.
  • Critical, major and minor defects should be defined before inspection because each class may use different acceptance limits.
  • Acceptance and rejection numbers apply to the inspected sample and provide a lot-level decision rule rather than a guarantee for every unit.
  • AQL is most useful when combined with a clear specification, defect catalogue, functional checks and instructions for handling critical findings.

Information the buyer should prepare

Prepare the topic-specific information below before requesting quotations, professional review or execution support.

  • The finished lot quantity and any rules for separating different models, colors, sizes or production batches.
  • The product specification, approved sample and measurable workmanship or functional requirements.
  • The defect definitions and classification of critical, major and minor nonconformities.
  • The intended inspection level, acceptance limits and any tests that must be performed outside the statistical sample.

Decision points before proceeding

Make these decisions explicitly before committing money, disclosing sensitive material or approving the next operational step.

  • Decide whether products can be treated as one inspection lot or require separate sampling by model or batch.
  • Define which safety, regulatory or functional failures require rejection regardless of normal AQL counts.
  • Select acceptance limits that reflect product risk and customer expectations rather than copying arbitrary supplier defaults.
  • Specify what happens after rejection, including sorting, rework, replacement, corrective evidence and possible re-inspection.

Topic-specific risks

Check these risks in the context of this guide rather than relying on a generic supplier statement.

  • The supplier describes AQL as permission to intentionally ship the stated percentage of defective products.
  • Undefined defect classes cause inspectors and buyers to count the same problem differently.
  • Mixed batches are sampled as one lot even though quality differs by production date, color or subcontractor.
  • A statistically accepted sample hides an untested safety or functional risk that required a separate mandatory check.

Worked example and practical next steps

Scenario: A buyer orders several thousand small electrical accessories and wants an objective pre-shipment workmanship decision. Analysis: The buyer defines critical electrical failures, major assembly defects and minor cosmetic issues, then selects sampling and acceptance limits before the inspection begins. Outcome: The report provides transparent defect counts and a documented acceptance decision while critical functional checks remain mandatory outside ordinary cosmetic sampling.

  • Define the inspection lot and separate materially different models or production batches.
  • Prepare an illustrated defect list with critical, major and minor classifications.
  • Agree the sampling level, acceptance limits and mandatory full or functional checks.
  • Record the rejection and corrective-action process before the inspector visits the supplier.