Short answer: AQL is the worst defect level that is still treated as acceptable when a batch is judged from a sample. It is a limit used to make inspection decisions, not a target for production.
What two sources say about AQL
| Source page | Publisher | What the page says |
|---|---|---|
| Acceptable quality limit | Wikipedia | Defines AQL as the poorest average defect rate a process can have and still be called acceptable, and pairs it with a rejectable quality limit. Notes the 2008 ANSI/ASQ wording change and says buyers and sellers agree an AQL before pre-shipment inspection. |
| Acceptable quality limit | QC Advisor | Describes AQL as a risk-based threshold used with a sample to judge a batch, and a planning input for a sampling plan. Says it is a limit, not a target, and names ISO 2859-1 and ANSI/ASQ Z1.4. |
Key points
- AQL is the poorest average defect rate still considered acceptable. [1]
- Buyers and sellers usually agree the AQL before pre-shipment inspection, based on the risk each accepts. [1]
- Defects are often grouped as critical, major or minor. [1]
- AQL is a boundary, not a goal; the name changed from level to limit to stress this. [2]
- AQL is an input to a sampling plan that sets sample size and accept or reject numbers. [2]
- Sampling plans commonly follow ISO 2859-1 or ANSI/ASQ Z1.4. [2]
AQL compared with Sampling plan
| Aspect | AQL | Sampling plan | Source |
|---|---|---|---|
| What it is | A planning threshold for the acceptable defect level. | A set of sample size plus accept and reject numbers. | [2] |
| What it decides | Whether a batch meets requirements, judged from a sample. | Accept or reject a lot by comparing defects found with the numbers. | [2] |
| How it is set | Agreed between buyer and seller before inspection. | Taken from sampling standards such as ISO 2859-1 or Z1.4. | [1, 2] |
Where sources differ
Expanded as acceptable quality limit, acceptable quality level or acceptance quality level. Wikipedia says the 2008 ANSI/ASQ change gave acceptance quality level; QC Advisor says acceptance quality limit. The meaning is the same.
Questions to ask a supplier about AQL
- [ ] Which AQL levels do you apply for critical, major and minor defects?
- [ ] Which sampling standard do you use?
- [ ] Who sets the inspection level and sample size?
- [ ] How are critical defects treated?
- [ ] What happens to a batch that fails?
Read next on this site
- Incoming Goods Inspection Checklist for Frames and Boards
- Incoming Goods Inspection Record Template (CSV)
- Sample vs Production Run: What Changes
More terms and explainers
- Bill of lading
- Commercial invoice
- Golden sample
- Quality Inspection Basics: Inspection Stages, AQL and Defect Classes
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Sources: [1] Wikipedia, fetched 2026-11-12; [2] QC Advisor, 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.