What AQL actually decides
AQL stands for Acceptable Quality Limit, and it's the rule an inspector uses to accept or reject your whole shipment after checking a sample of it. It comes from one standard: ANSI/ASQ Z1.4 in the US, which is identical to ISO 2859-1 used elsewhere (both descend from the old military standard MIL-STD-105E). When people ask "what AQL level should I use," they're really choosing two separate things. The first is the General Inspection Level, which decides how many pieces the inspector pulls from the lot. The second is the AQL number itself, which decides how many defective pieces the inspector will tolerate in that sample before the lot fails. Set both correctly and you get a check that's strict enough to catch real problems without paying an inspector to count your entire order.
The default that covers most orders
For ordinary consumer goods from a supplier you've used before, the standard setting is General Inspection Level II with a 2.5 AQL on major defects and 4.0 on minor defects, and zero tolerance on critical defects. This is what every major third-party inspection firm (SGS, QIMA, Bureau Veritas, Intertek, TÜV Rheinland) puts on a quote by default, and it's what a buyer means by "standard AQL" without spelling it out. Level II pulls a sample sized to your lot. A 5,000-piece order, for example, draws a 200-piece sample. At 2.5 on majors, that 200-piece sample accepts up to 10 major defects and rejects at 11. If you do nothing else, this is the line to put in your purchase order.
When should you make it stricter?
Move up to General Inspection Level III, a tighter major limit (1.5 instead of 2.5), or both, whenever the downside of a bad lot is bigger than usual:
- A first order from a new supplier, where you have no inspection history to lean on.
- Goods that touch safety: anything electrical or battery-powered, anything a child handles, anything worn on or in the body.
- High unit value, where a few percent of rejects is real money.
- A branded product where one visible flaw damages more than the single unit.
Level III pulls a larger sample for the same lot, so it catches a defect rate that Level II might sample straight past. A 1.5 major AQL simply lowers the number of major defects you'll accept before rejecting. Both cost a little more inspection time and bounce more borderline lots. On a first order, that's exactly the trade you want.
When can you use a lighter check?
Drop to General Inspection Level I when you have a proven supplier, a simple product, and a run of clean inspections, and you want a faster, cheaper check that still gives you a statistical read. Level I pulls a smaller sample, so it's less sensitive, which suits low-risk repeat business and is wrong for a first run. Separately, the standard offers Special Inspection Levels S-1 to S-4 with very small samples for tests you can't run on hundreds of units: a drop test, a function test, a tear-down, anything destructive or slow. You'd run general Level II on appearance and a special level on a function test in the same inspection.
Critical, major, minor: define them first
The AQL number is meaningless until you say what counts as each class of defect, and that job is yours, not the inspector's. The three classes are standard:
- Critical: a defect that makes the product unsafe or illegal to sell. The AQL is 0. One found, the lot fails.
- Major: a defect a customer would notice and return the product for, such as wrong function, wrong size, or an obvious cosmetic fault. Default AQL 2.5.
- Minor: a small flaw most buyers would accept, like a faint mark or a slightly loose thread. Default AQL 4.0.
Write your own defect list per product and attach it to the purchase order alongside the golden sample, so "major" means the same thing to your inspector in Shenzhen as it does to you. Without that list, two inspectors will hand you two different verdicts on the same goods.
Read the number, not just the pass
An inspection comes back as a sampling result: the sample size, the accept and reject numbers (written Ac and Re), and the count of defects found in each class. A pass at 9 majors against an accept of 10 is a pass sitting one unit from failure, and it tells you to tighten next time or hold the balance payment until you've seen corrected goods. The point of AQL is the number behind the stamp: how close the lot ran to the edge.
Where Mila Sourcing fits
We set the inspection level and the AQL with you before production starts, write the defect list against your golden sample, and book the third-party inspector, so the report that decides your balance payment is built on numbers you chose, not a default someone on the factory side picked. That's part of Sourcing Activation and Full Production Management.
Related, if you're setting up quality control right now: