Understanding AQL: how sampling inspection really works for China imports
Every quality control quote says “AQL 2.5” — but what does that mean concretely: how many cartons get opened, how many defects are allowed, and when does shipment stop? Here is the system behind world trade’s most important inspection method.
5 min read · For buyers and retailers
The principle: inspecting without inspecting everything
A 100 % inspection of 10,000 pieces makes no economic sense for consumer goods. ISO 2859-1 solves this statistically: the lot size determines a sample size via sampling plans (e.g. 200 pieces for a 10,000 lot at inspection level II), and the agreed AQL value defines how many defects are acceptable in that sample.
Defects are classified: critical defects (safety risk, illegal) carry AQL 0 — a single one rejects the lot. Major defects (product unsellable: scratches on visible surfaces, functional failure) typically run at AQL 2.5. Minor defects (small cosmetic flaws) at AQL 4.0. This “0 / 2.5 / 4.0” combination is the de facto standard for consumer goods.
What a good inspection report contains
A useful report documents more than “passed”: lot size and drawn sample, defect list with photos per finding, dimensional and functional spot checks, packaging and carton checks (drop test, markings), and the clear result: accepted or rejected, with counters per defect class. Our sample inspection report shows what this looks like in practice.
Timing is decisive: inspection belongs at the end of production but before loading (“pre-shipment inspection”, at 80–100 % completion). Only then can the manufacturer rework defects at their own cost, and only then is your payment still leverage. Inspecting after shipment means complaining instead of negotiating.
When AQL is not enough
AQL checks visible and functional defects — not chemistry and not durability. Restricted substances (REACH, LFGB), material composition and fatigue strength need lab tests running parallel to the AQL inspection. And for safety parts (load-bearing components, electrics), tightened or 100 % inspection of individual characteristics replaces sampling.
The second limit: AQL measures against a specification. If the specification is vague (“good quality”), the inspector checks against thin air. Quality assurance therefore starts not on inspection day but at ordering: a frozen reference sample, written inspection criteria, defined defect classes per article. That is exactly how we set up every inspection.
Common questions about AQL inspection
Does AQL 2.5 mean 2.5 % scrap may be delivered?
Not quite — AQL is the quality level that is on average just still accepted, not a scrap guarantee per delivery. Practically: at AQL 2.5 with a 200-piece sample, the lot is accepted with up to 10 major defects and rejected from 11. If you need less tolerance, agree AQL 1.5 or 1.0 — at correspondingly higher inspection or production cost.
What happens when an inspection fails?
Three paths, in this order: rework by the manufacturer with re-inspection (the standard case, at the factory’s cost), sorting the batch (separating good from bad pieces), or — for structural defects — new production or price negotiation. What matters is that the final payment only flows after a passed inspection; that is exactly how we structure payment plans.
Is one inspection per supplier enough, or every batch?
Every batch — with new suppliers, quality is a process, not a state. After several defect-free batches you can switch to reduced inspection severity under ISO 2859 (smaller sample, lower cost) and automatically switch back when problems appear. This dynamic system is a built-in part of the standard — and of our inspection plans.
Related topics
Have your next batch inspected?
Also for suppliers you already use: define the inspection plan, inspector into the factory, report before shipment — just send an inquiry.