What AQL Actually Means
AQL (Acceptance Quality Limit) is the worst tolerable defect rate in a batch that you will still accept. It is written as a percentage: AQL 2.5 means you accept a shipment with up to 2.5% defective units, provided the number of defects found in the inspected sample does not exceed the plan's allowance. It is not a promise that 97.5% are perfect — it is a statistically derived acceptance line.
Key point: AQL is for defects, not for every measurement. Critical defects (safety, regulatory) are usually rejected at zero regardless of AQL. AQL governs major and minor defects — things like a misaligned print, a loose stitch, a wrong-label placement.
Which AQL Level Should You Use?
For apparel, three levels cover almost every buyer. Pick based on how visible the defect is to the end customer and how much risk you carry.
| AQL level | Use for | Typical buyer |
|---|---|---|
| AQL 1.0 | Premium / branded / high-visibility defects. Very tight allowance. | Established brands, EU retailers |
| AQL 2.5 | Standard commercial apparel. The most common default in the industry. | Most mid-market brands |
| AQL 4.0 | Basic / promotional / low-risk goods where minor flaws are acceptable. | Promo, giveaways |
How Sample Size Is Decided (Inspection Level II)
AQL plans use a statistical table (ANSI/ASQ Z1.4, the international equivalent of ISO 2859-1). You pick an inspection level — General Inspection Level II is the default for apparel — and the lot size determines how many pieces get checked. You do not inspect the whole order; you inspect a scientifically sized sample.
| Lot size (pcs) | Sample size (Level II) | Max defects allowed @ AQL 2.5 |
|---|---|---|
| 2 – 8 | 2 | 0 |
| 9 – 15 | 3 | 0 |
| 151 – 280 | 20 | 1 |
| 501 – 1,200 | 32 | 2 |
| 3,201 – 10,000 | 80 | 5 |
| 35,001+ | 200 | 14 |
Note: these are illustrative ranges from the standard sampling plan. The exact accept/reject numbers come from the official AQL table for your chosen level and AQL.
How a Cotton Knitwear Factory Holds Pass Rate Above 99%
AQL is the buyer's acceptance line; a factory's own pass rate is built upstream, before inspection. At SILAMON the blockers are designed in, not bolted on:
- In-line checking at each process (cutting, sewing, printing, finishing) catches issues while they are still cheap to fix — not at the final gate.
- A sealed reference sample (the approved pre-production sample) sits on the line so every operator matches the same standard.
- Major-defect prevention: needle detection, correct label/heat-transfer placement checks, and size-run verification before cartoning.
- AQL 2.5 final audit on outgoing lots, with the result reported back to you per shipment.
Buyer tip: State your AQL and inspection level in the tech pack and the PO, not just verbally. A written AQL 2.5 / Level II means the same thing to the factory's QC and to a third-party inspector you might hire later — removing ambiguity about what “good enough” means.
Writing AQL Into Your Order
- Specify: “Final inspection AQL 2.5, General Level II, single sampling, ANSI/ASQ Z1.4.” Adjust the level for premium (1.0) or basic (4.0) goods.
- Define major vs minor defects in advance (e.g., a 2 mm print shift = major; a stray thread = minor) so the inspector applies your rules, not theirs.
- Request the inspection report with photos per shipment — it doubles as your incoming QC record.
FAQ
What does AQL actually mean?
AQL (Acceptance Quality Limit) is the worst tolerable defect rate in a batch that you will still accept, written as a percentage. AQL 2.5 means you accept a shipment containing up to a defined number of defects for the sample size inspected — it is a risk threshold, not a zero-defect promise.
Which AQL level should I use for apparel?
Three levels cover almost every buyer. Use AQL 1.0 for premium goods where a defect is highly visible, 2.5 as the standard for most apparel, and 4.0 for basic or promotional goods where minor defects are acceptable. Choose by how visible the defect is to the end customer and how much risk you carry.
How is the inspection sample size decided?
Sampling plans use a statistical table (ANSI/ASQ Z1.4, the international equivalent of ISO 2859-1). You choose an inspection level — General Inspection Level II is the default for apparel — and the lot size then determines how many pieces are pulled. The exact accept/reject numbers come from the official table for your chosen level and AQL.
Can I write AQL requirements into my order?
Yes, and you should. Specify it explicitly: "Final inspection AQL 2.5, General Level II, single sampling, ANSI/ASQ Z1.4." Adjust to 1.0 for premium goods or 4.0 for basic. Define major versus minor defects in advance — for example a 2 mm print shift is major, a stray thread is minor — so the inspector applies your rules, not theirs.