AQL 2.5/4.0, explained like you’re on the line

What AQL actually promises

AQL — acceptance quality limit — is not a defect rate promise. It is a statistical contract: sample this many pieces from the lot, and if defects stay at or under the accept number, the lot passes at that quality limit. The trade default for garments is AQL 2.5 for major defects (would cause a return) and 4.0 for minors (noticeable, not returnable) — with critical defects (safety — needles, mold) accepting exactly zero, always.

The table, in one worked example

Say a lot of 8,400 boxers is offered for final inspection. ANSI Z1.4 at General Inspection Level II maps 3,201–10,000 pieces to code letter L: inspect 200 pieces. At AQL 2.5, accept 10 majors, reject at 11; at AQL 4.0, accept 14 minors, reject at 15. Five numbers — that is the whole decision.

Two details separate professionals: the sample comes from the offered lot quantity, never the PO quantity (partial offers get smaller samples, honestly), and the verdict follows the table mechanically — eleven majors is a fail even the day before shipment. If it can be argued with, it isn’t AQL.

Reading a report in ninety seconds

Check, in order: the lot quantity against what was actually ready; the code letter and sample size against the table; defects listed with photos (a report without photographs is an opinion); measurements against tolerance, with out-of-tolerance counted as majors; and the verdict — computed, with any override carrying a written reason. Where the process runs on software, overrides stay recorded forever; in our platform that’s structural, not policy.

What to require from any supplier

Written sampling standard (ANSI Z1.4 or ISO 2859-1), stated AQLs per defect class, photographed findings, measurement audits with tolerance math, and inspection dates confirmed by all three parties before goods are offered. Any partner who resists any of these is telling you how their bad weeks go.