In short
AQL means Acceptance Quality Limit. It is the sampling standard (ISO 2859-1) used in almost every product inspection in China. Two tables tell the inspector how many units to check for a given order quantity, and how many defects are accepted before the lot is rejected. Our default plan is General Inspection Level II, zero critical defects, AQL 2.5 for major defects and AQL 4.0 for minor defects.
What is AQL? Meaning and definition
Most inspections in Chinese factories are prepared and carried out by inspectors who follow the AQL standard. AQL stands for Acceptance Quality Limit (it was called Acceptable Quality Level in older editions). It is defined by the international standard ISO 2859-1; the American ANSI/ASQ Z1.4 and the former MIL-STD-105E use the same tables.
In practice, AQL gives the buyer two numbers: how many products to inspect, and the maximum number of defects accepted in that sample. The AQL value itself (0.65, 1.0, 1.5, 2.5, 4.0…) is the quality level you set: the lower the value, the stricter the inspection.
To use AQL well, the buyer must first do two things: write a clear list of checkpoints, and decide the quality level expected for each type of defect. We cover both below.
Why use AQL rather than checking every unit?
1. It saves time and cost
Take 2,500 tablets that need 2 minutes of tests each. Checking every unit takes about 11 inspector-days. An AQL sample of 125 units takes one inspector one day. No factory will hold finished goods and workers for two weeks of checks, and you do not want to ship two weeks late.
2. It limits waste
Some tests damage or destroy the product (drop test, opening a sealed unit, cutting a seam). Testing a small, statistically chosen sample keeps the rest of the order sellable.
3. Why not a fixed percentage?
The AQL sample grows much more slowly than the order. At Level II, 1,000 units need a sample of 80, and 10,000 units need 200. A fixed 10% would mean checking 1,000 units on a 10,000-unit order, for very little extra certainty.
The AQL tables
The standard has two tables. Table A gives a sample size code letter from the lot size and the inspection level. Table B turns that letter into a sample size and gives, for each AQL value, the accept (Ac) and reject (Re) numbers.
How to read the AQL tables
Table A: find the sample size code letter
- Lot size: the quantity of one product reference in the order. Different products, or variants inspected separately, are different lots.
- General inspection levels I, II and III: Level II is the default. Level III gives a larger sample (more certainty, higher cost); Level I a smaller one (lower cost, more risk).
- Special inspection levels S-1 to S-4: very small samples, used for long or destructive tests (function tests, drop tests, detailed measurements) where checking many units is not practical.
- Code letter: where the lot-size row meets the level column. For 2,500 units at Level II, the letter is K.
Table B: sample size, Ac and Re
- Sample size: the letter gives the number of units to pick at random across the whole lot (K = 125 units).
- AQL value: the column for the quality level set for each defect category, for example 2.5 for major defects.
- Ac (accept): the maximum number of defects found in the sample for the category to pass.
- Re (reject): from this number of defects, the category fails.
- Arrows: when the cell shows an arrow, use the first sampling plan below (↓) or above (↑) it, with its own sample size and Ac / Re numbers.
Each defect category is judged separately. If one category fails, the whole lot fails.
Critical, major and minor defects
- Critical: can harm the user or breaks a regulation. Examples: accessible live parts, sharp edges on a children’s product, missing mandatory safety marking. Usually zero tolerance.
- Major: makes the product unsellable or likely to come back, without safety risk. Examples: function not working, torn seam, wrong colour, dimension out of tolerance.
- Minor: a small deviation, only unacceptable in large numbers. Examples: light scratch on a hidden surface, small dirt mark, slightly uneven stitching.
Position matters: a scratch on the back of a cabinet is minor, the same scratch on a glass door may be major. These rules are written into the inspection checklist, so the factory and the inspector apply the same ones.
Defining the checkpoints
AQL says how many defects you accept; it does not say what a defect is. Before the inspection, we prepare a checklist with you:
- product specifications and tolerances: dimensions, weight, materials, colour compared with the approved sample;
- workmanship and finish;
- functions and on-site tests;
- marking, labels, packaging and carton drop test;
- for each point, whether a deviation counts as critical, major or minor.
To see how these checkpoints appear in a real report, read our guide to quality control and inspection reports in China.
Worked example: 2,500 units
2,500 units fall in the 1,201–3,200 range. At Level II, that gives code letter K and a random sample of 125 units. With our default plan:
- Critical defects, zero tolerance: accept 0, reject at 1.
- Major defects, AQL 2.5: accept up to 7, reject at 8.
- Minor defects, AQL 4.0: accept up to 10, reject at 11.
With 0 critical, 5 major and 12 minor defects, the lot passes on critical and major defects but fails on minor ones. The overall result is a fail: the factory sorts or reworks the goods, and the lot is inspected again.
AQL table: reference values (Level II, single sampling, normal inspection)
| Lot size | Code letter | Sample size | AQL 0.65 (Ac / Re) | AQL 1.5 (Ac / Re) | AQL 2.5 (Ac / Re) | AQL 4.0 (Ac / Re) |
|---|---|---|---|---|---|---|
| 151–280 | G | 32 | ↑ use 0 / 1 on 20 | 1 / 2 | 2 / 3 | 3 / 4 |
| 281–500 | H | 50 | ↓ use 1 / 2 on 80 | 2 / 3 | 3 / 4 | 5 / 6 |
| 501–1,200 | J | 80 | 1 / 2 | 3 / 4 | 5 / 6 | 7 / 8 |
| 1,201–3,200 | K | 125 | 2 / 3 | 5 / 6 | 7 / 8 | 10 / 11 |
| 3,201–10,000 | L | 200 | 3 / 4 | 7 / 8 | 10 / 11 | 14 / 15 |
| 10,001–35,000 | M | 315 | 5 / 6 | 10 / 11 | 14 / 15 | 21 / 22 |
Read a line like this: for 3,201 to 10,000 units, check 200 units at random; at AQL 2.5, the lot passes with up to 10 defects and fails at 11.
Which AQL level should you choose?
- Start from our default: Level II, zero critical, AQL 2.5 major, AQL 4.0 minor. It suits most consumer and furniture orders.
- Go stricter on demanding or high-value products: AQL 1.5, 1.0 or 0.65 for major defects (electronics, medical, premium goods).
- Change the level, not only the AQL: Level III gives a larger sample and more certainty, at a higher cost.
- Keep tests apart: function, safety and destructive tests run on a small special-level sample or on every unit, and are reported separately.
Is AQL enough?
AQL is a statistical check of visual and dimensional quality on a random sample. It does not prove compliance with regulations (CE marking, REACH, fire standards): lab tests do. It does not replace a factory audit before the first order, or a check during production that catches problems while they can still be fixed.
On the orders we manage, AQL inspection sits within a sequence: supplier audit before the first deposit, inspection during production when needed, pre-shipment inspection before the balance is paid, and loading supervision.
A word of advice from our team
Agree the AQL plan and the checklist with the factory before production starts, in the purchase order or the contract. A factory that knows the rules from day one has no reason to dispute the result. Keep an approved, signed sample, and pay the balance only after a passed final inspection.
AQL: frequently asked questions
What does AQL stand for?
AQL stands for Acceptance Quality Limit, formerly Acceptable Quality Level. It is the sampling method of ISO 2859-1 used in product inspections.
What does AQL 2.5 mean?
AQL 2.5 is the quality level set for a defect category, usually major defects. On a sample of 125 units (code letter K), it means up to 7 major defects are accepted and the lot is rejected at 8.
What does AQL 1.5 or AQL 0.65 mean?
They are stricter levels. On a sample of 125 units, AQL 1.5 accepts up to 5 defects and AQL 0.65 up to 2. They are used for high-value or sensitive products.
What is the difference between inspection levels I, II and III?
The level sets the sample size for a given lot. Level II is the standard; Level III takes a larger sample for more certainty, Level I a smaller one.
What AQL is used for critical defects?
Critical defects are usually set to zero tolerance: one critical defect found in the sample fails the lot.
How much does an AQL inspection cost in China?
At Asiaction, a product inspection costs $349 per man-day, all-inclusive anywhere in China. The full report with photos and videos is sent the next day; book 48 hours in advance.
Have your next order inspected
Send us the product, the quantity and the factory location. We propose an AQL plan and a checklist, and our inspectors in China check your goods before you pay the balance. Learn more about our product inspection service.
