Short answer: AQL (acceptance quality limit) is the worst tolerable process average used to set a sampling plan: the lot size and inspection level give a sample size, and the plan gives the number of defects at which the lot is accepted or rejected. Inspections are usually done before production, during production and before shipment, and defects are classed as critical, major or minor, each with its own AQL.
Inspection stages
| Stage | Typical timing (varies by source) | What it checks | Source |
|---|---|---|---|
| Pre-production or initial production check | About 0-10% complete (source 3); 0-20% (source 4) | Raw materials, components and set-up against the approved sample and the materials the buyer specified; first units against the golden sample; line audit | [3, 4] |
| During production inspection | About 20-60% (source 3); 20-80% (source 4) | Catches systemic problems such as colour mismatch while the factory can still correct remaining units | [3, 4] |
| Pre-shipment inspection | 80-100% produced and at least 80% packed (source 3) | Random AQL sample: workmanship, function, dimensions, weight, packaging, labelling and shipping marks; pass/fail report | [3] |
| Container loading check | During loading (source 3) | The inspector supervises loading; cargo is loaded and the container sealed | [3] |
Inspection stages and what each checks
How an inspection runs
- Set the standard. Agree the AQL standard, inspection level and the AQL for each defect class in writing. [1, 2, 3]
- Pre-production check. Verify materials, components and set-up against approved sample and specification. [3, 4]
- During-production check. Look for systemic defects while corrections are still possible. [3]
- Pre-shipment inspection. Draw a random sample from the packed lot and count defects by class. [2, 3]
- Decide. Accept if defects are at or under the accept number for each class, otherwise reject, per the sampling plan. [1, 2]
- Optional loading check. Supervise the loading of the cartons. [3]
Checklist for an inspection agreement
- [ ] Agree AQL values for critical, major and minor defects in writing before inspection [3]
- [ ] Define what counts as critical, major and minor with your inspector [3, 4]
- [ ] State the standard used, such as ISO 2859-1 or ANSI/ASQ Z1.4 [1, 2, 3]
- [ ] State the inspection level, with General Level II the usual default [1, 3]
- [ ] Treat zero critical defects as the usual target [1, 2]
- [ ] Compare first production units with the approved sample [3, 4]
- [ ] Check materials before production, not only at the end [3, 4]
- [ ] Schedule a during-production check to catch repeating defects early [3]
- [ ] Run pre-shipment inspection when goods are at least 80% packed [3]
- [ ] Ask for a pass/fail report with photos [3, 4]
- [ ] Confirm that packed quantities match the packing list (general practice)
Cautions
- Stage percentages differ between sources; set exact windows in your contract.
- The 0/2.5/4.0 AQL values are common conventions, not fixed rules; the ASQ and ISO pages could not be fetched, so the standard's tables should be checked directly.
- General information, not legal advice.
Related pages on this site
| Page on this site | What it holds |
|---|---|
| Incoming Goods Inspection Checklist for Frames and Boards | Incoming goods inspection checklist |
| Incoming Goods Inspection Record Template (CSV) | Inspection record template |
| Sample vs Production Run: What Changes | Sample and production run |
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Sources: [1] Acceptable Quality Level (AQL) (iSixSigma, fetched 2026-11-12); [2] AQL: Acceptable Quality Limit (QIMA, fetched 2026-11-12); [3] Comprehensive Guide to China Inspection Services for Importers (China2West, fetched 2026-11-12); [4] Initial Product Inspection: Catching Issues Before Production Scales (HQTS, fetched 2026-11-12). As of 2026-11-12. General information, not legal, customs or tax advice. Wording is paraphrased from the pages linked; your written quote and contract govern.