Jul 27, 2026AQL & Quality Standards
How Many Pieces Are Inspected During a Quality Inspection? A Simple Guide to AQL Sampling Plans
Learn how inspection quantity is decided using AQL sampling plans, lot size, inspection level, code letter, sample size, and accept/reject criteria.
When arranging a product inspection, many importers ask one simple question: how many pieces will actually be checked?
The answer is usually not a fixed percentage of the order. A professional inspection company normally uses an AQL sampling plan to decide the inspection quantity. The sample size is based on the order quantity, inspection level, and agreed AQL limits.
For buyers sourcing from China, this matters because the inspection quantity is not chosen casually by the inspector. It follows a recognized sampling method used to select representative samples and support a practical shipment decision.
Why Inspectors Do Not Check Every Product
Many shipments contain hundreds, thousands, or tens of thousands of pieces. Checking every unit is called 100% inspection. It is possible in some situations, but it takes more time, costs more, and is not necessary for many normal commercial shipments.
AQL sampling gives importers a practical method. Instead of checking every piece, the inspector checks a defined sample size from the inspection lot and compares the findings with agreed acceptance criteria.
Sampling does not guarantee that every defect in the shipment will be found. It helps the buyer make a reasonable quality decision based on representative samples.
If a shipment has repeated defects, safety concerns, or needs rework verification, the buyer may choose a stricter approach. In some cases, Product Sorting Service or 100% checking may be more suitable.
How Inspection Quantity Is Decided
Inspection quantity is decided step by step:
Order Quantity → Lot Size → Inspection Level → Code Letter → Sample Size → AQL Acceptance Criteria
The inspector first confirms the lot size. Then the inspection level is applied. Table A gives a code letter. Table B uses that code letter to show the sample size and accept/reject numbers.
Table A includes both Special Inspection Levels and General Inspection Levels, so the buyer must confirm which level should apply before the sample size is calculated.
For many normal consumer goods inspections, General Inspection Level II is commonly used. Buyers may choose a different level when the product risk, budget, or inspection purpose requires it.
Step 1: Understand Lot Size and Inspection Level
Lot Size means the total quantity of products included in the inspection lot.
If 8,000 pieces are ready and submitted for inspection, the lot size is normally 8,000 pieces. If only 3,000 pieces are finished and the buyer asks to inspect only those finished goods, the lot size may be 3,000 pieces.
The lot size must be clear before using the AQL tables.
General Inspection Levels are usually used for normal product inspections:
- Level I: smaller sample size
- Level II: common choice for normal inspections
- Level III: larger sample size
Special Inspection Levels are usually shown as S-1, S-2, S-3, and S-4. They are used when only a smaller sample size is needed, such as limited checks or tests where checking many pieces is not practical.
For a normal Pre-Shipment Inspection, General Level II is often the starting point unless the buyer specifies otherwise.
Step 2: How to Read Table A: Lot Size to Code Letter
Table A does not directly tell you how many pieces to inspect.
It gives a Code Letter based on the lot size and inspection level. That code letter is then used in Table B.
Table A: Lot Size to Code Letter
Lot Size | Special Inspection Levels | | | | General Inspection Levels | | |
|---|---|---|---|---|---|---|---|
| S-1 | S-2 | S-3 | S-4 | I | II | III |
2-8 | A | A | A | A | A | A | B |
9-15 | A | A | A | A | A | B | C |
16-25 | A | A | B | B | B | C | D |
26-50 | A | B | B | C | C | D | E |
51-90 | B | B | C | C | C | E | F |
91-150 | B | B | C | D | D | F | G |
151-280 | B | C | D | E | E | G | H |
281-500 | B | C | D | E | F | H | J |
501-1,200 | C | C | E | F | G | J | K |
1,201-3,200 | C | D | E | G | H | K | L |
3,201-10,000 | C | D | F | G | J | L | M |
10,001-35,000 | C | D | F | H | K | M | N |
35,001-150,000 | D | E | G | J | L | N | P |
150,001-500,000 | D | E | G | J | M | P | Q |
500,001 and above | D | E | H | K | N | Q | R |
Example:
Shipment quantity: 8,000 pcs
Inspection level: General Level II
In Table A, 8,000 pcs falls into the 3,201-10,000 range. Under General Level II, the code letter is L.
The next step is to use Code Letter L in Table B.
Step 3: How to Read Table B: Code Letter to Sample Size and Ac/Re
Table B uses the Code Letter to decide the sample size.
It also gives the acceptance number and rejection number for each AQL level.
Ac means the maximum number of defects allowed for that defect category.
Re means the number at which the lot is rejected for that defect category.
Example Table B: Sample Size and Acceptance Numbers for Common Inspection Situations
Code Letter | Sample Size | Critical AQL 0 Ac/Re | Major AQL 2.5 Ac/Re | Minor AQL 4.0 Ac/Re |
|---|---|---|---|---|
H | 50 | 0/1 | 3/4 | 5/6 |
J | 80 | 0/1 | 5/6 | 7/8 |
K | 125 | 0/1 | 7/8 | 10/11 |
L | 200 | 0/1 | 10/11 | 14/15 |
M | 315 | 0/1 | 14/15 | 21/22 |
This is a simplified excerpt for common inspection situations. Full AQL tables include more code letters, more AQL levels, and arrow rules.
If a cell shows an arrow in the full table, the inspector follows the direction shown in the table. This may mean using the sampling plan above or below that row. For buyers, the important point is simple: the inspector is not guessing. The table tells which plan to use.
Using the earlier example, Code Letter L gives a sample size of 200 pcs.
If the buyer uses AQL 2.5 for major defects, the Ac/Re is 10/11. If the inspector finds 10 or fewer major defects in the checked sample, the major defect result is acceptable. If 11 or more major defects are found, the lot fails for major defects.
Example: How a 15,000 Piece Order Gets Its Inspection Quantity
Suppose an importer has a 15,000-piece order ready for inspection.
Inspection level: General Level II
Critical defects: AQL 0
Major defects: AQL 2.5
Minor defects: AQL 4.0
First, find the lot size range in Table A. A 15,000-piece order falls into the 10,001-35,000 range.
Under General Level II, the code letter is M.
Then go to Table B. Code Letter M gives a sample size of 315 pcs.
The inspector selects 315 pieces from the shipment. These samples should come from different cartons or packing locations, not only from pieces prepared by the factory.
After checking the 315 pieces, the inspector compares the defects found with the AQL acceptance numbers:
Critical defects: accept 0, reject 1 or more
Major defects at AQL 2.5: accept 14 or fewer, reject 15 or more
Minor defects at AQL 4.0: accept 21 or fewer, reject 22 or more
This is how the inspection quantity and final inspection decision are connected.
Why Does My Inspection Report Show Only 200 Pieces Checked?
First-time importers are sometimes surprised when an inspection report says 200 pieces were checked from an 8,000-piece shipment.
This does not mean the inspection was incomplete. In the example above, 8,000 pieces under General Inspection Level II gives Code Letter L, and Code Letter L gives a sample size of 200 pieces.
The number comes from the agreed sampling plan. It is based on the lot size, inspection level, and AQL requirements, not on a fixed percentage of the order.
The inspector should still select the 200 pieces properly. Samples should come from the shipment lot, usually from different cartons or packing locations, so the checked pieces can represent the goods submitted for inspection.
The purpose of sampling is not to check every unit. It is to use a recognized method to select representative samples and help the buyer make a practical shipping decision.
What AQL Means in the Inspection Result
AQL is often misunderstood.
It does not mean the buyer agrees that the same percentage of the full shipment can be defective. AQL is not a direct estimate of the total defect rate in the order.
AQL defines the acceptance criteria used for the inspected sample. During inspection, defects are usually classified as critical, major, or minor, then compared with the agreed Ac/Re numbers.
Critical defects are usually safety, compliance, or serious usability issues. Major defects may affect product use, saleability, appearance, or customer acceptance. Minor defects are smaller issues that may not affect function but still need to be controlled.
The AQL result becomes much clearer when the buyer has already defined what should count as critical, major, or minor before inspection.
Why Inspection Level and Product Risk Matter
The same order quantity can lead to different sample sizes if the buyer chooses a different inspection level.
General Level I means fewer samples. General Level III means more samples. Special levels mean smaller sample sizes for certain limited checks.
The right level depends on the product and the buyer’s risk tolerance.
For a simple low-risk item, General Level II may be enough. For a new supplier, a first order, or a product with repeated quality issues, the buyer may choose a stricter approach. For destructive testing, the buyer may use a special inspection level or send selected samples for lab testing.
AQL decides how many pieces are checked. It does not replace product-specific judgment.
For example, two products may both require a 200-piece sample size, but the inspection focus will be different. A garment inspection may focus on measurements, workmanship, shade, labels, and packing. An outdoor product may require more function and strength checks. A safety-related item may need independent testing in addition to inspection.
This is why buyers should not only ask, “How many pieces will be inspected?” They should also confirm what will be checked on those pieces.
What Importers Should Provide Before Inspection
Before inspection, the buyer should confirm the total order quantity, product information, inspection level, AQL requirements, and any special quality requirements.
If there is an approved sample, specification sheet, packing instruction, artwork, measurement tolerance, or testing requirement, it should be provided before the inspection date.
The buyer should also clarify whether the inspection lot includes the full order or only the finished portion available at the factory.
If samples need to be selected for buyer review or testing, Sample Picking Service can help confirm that samples are selected from the correct goods and properly recorded.
If formal performance testing is needed, Lab Testing Assistance Service can help coordinate testing after representative samples are selected.
Clear instructions help the inspector apply the right sampling plan and focus on the issues that matter for the product.
Final Thought
A sampling plan is used to select representative samples through a recognized method and help importers make informed shipping decisions.
For buyers sourcing from China, understanding lot size, inspection level, code letter, sample size, and Ac/Re numbers makes inspection reports easier to read. It also helps avoid confusion when a report says 200 pieces were checked from an 8,000-piece shipment, or 315 pieces were checked from a 15,000-piece shipment.
The purpose of AQL sampling is not to inspect every product. It is to give the buyer a practical, consistent way to evaluate shipment quality before release.