How to Read AQL Sampling Results for China Factory Inspections

When a China factory inspection report says “AQL 2.5,” “Sample Size 125,” “Major: Ac 7 / Re 8,” or simply “PASS,” many overseas buyers are not sure what those numbers actually mean.

The key point is that AQL inspection is a sampling-based acceptance decision. The inspector does not normally check every unit in the order. Instead, a defined number of units is selected from the lot, defects are classified, and the findings are compared with predetermined acceptance and rejection criteria.

That means you should not read an AQL report as if it were a simple calculation of the percentage of defective products in the entire order.

If you are comparing inspection providers before arranging an inspection, it is also useful to understand what a proper inspection service should provide. Once the inspection is performed, however, the AQL section of the report becomes especially important because it tells you how the sampled results were evaluated.

What Does AQL Mean in a China Factory Inspection?

AQL stands for Acceptance Quality Limit.

In an acceptance sampling system, AQL is one of the parameters used to select an appropriate sampling and acceptance plan. It is not simply a statement that “this percentage of the order is allowed to be defective.”

This distinction is important.

For example, if an inspection instruction specifies a Major AQL of 2.5, you should not assume that 2.5% of the entire order may contain major defects.

The actual inspection decision depends on several things working together:

• Lot size
• Inspection level
• Sampling plan
• Sample size
• AQL value
• Defect classification
• Acceptance number (Ac)
• Rejection number (Re)

The sampling plan determines how many units are inspected and how many counted defects can result in acceptance or rejection.

This is why simply looking at the AQL number is not enough to understand an inspection result.

AQL is also different from your product quality specification. Your own requirements may be much stricter than the sampling plan. For example, a product specification may define a particular cosmetic defect as unacceptable even though the sampling plan contains a numerical acceptance criterion for that defect class.

Your product requirements and the sampling plan therefore need to work together.

How Does Lot Size Affect the Sample Size?

The lot size is the quantity represented by the inspection.

Suppose a Chinese factory has completed a large order and the buyer asks for a pre-shipment inspection. The inspector needs to know how much finished production is being presented for inspection.

The sampling plan then determines the sample size based on the applicable inspection procedure and inspection level.

This does not mean that the sample always equals a fixed percentage of the order.

For example:

The exact sample size should therefore come from the applicable sampling standard or agreed inspection procedure, rather than from a rule such as “inspect 10% of the order.”

This is one reason buyers should ask an inspection provider to state the lot size, inspection level, sample size, and acceptance criteria in the inspection instructions.

For buyers comparing factory inspection services, these details are much more useful than simply asking whether the company “offers AQL inspection.”

What Do AQL 1.0, 1.5, 2.5 and 4.0 Actually Mean?

You will often see AQL values such as:

• 1.0
• 1.5
• 2.5
• 4.0

These numbers are parameters within the sampling system.

A lower AQL generally corresponds to a stricter acceptance criterion than a higher AQL when the other sampling conditions are the same.

But it is important not to interpret them as a simple percentage allowance.

For example:

AQL 2.5 does not mean “2.5% of the inspected products can be defective and the order automatically passes.”

The acceptance number comes from the sampling plan. It is possible for the number of defects required to reject a sample to be different from simply multiplying the sample size by 2.5%.

This is also why two reports with the same AQL value can have different sample sizes or Ac/Re values if other sampling parameters are different.

A buyer should therefore read the complete combination rather than focusing on the AQL number alone.

What Should Buyers Confirm Before Inspection?

Before the inspector visits the factory, confirm:

1. What quantity is included in the inspection lot?
2. Which inspection level is being used?
3. How many units will be sampled?
4. Which AQL values apply to each defect class?
5. How are Critical, Major and Minor defects defined?
6. What are the applicable Ac/Re limits?
7. What product specifications or approved samples will be used?

This is where clear quality acceptance criteria become important.

A sampling plan cannot replace a clear product specification. If the buyer and factory have never agreed on what constitutes an acceptable product, an AQL number alone will not solve that problem.

Critical, Major and Minor Defects: What Is the Difference?

AQL reports commonly separate defects into Critical, Major and Minor categories.

These classifications describe the seriousness of a defect. They should be defined according to the product, applicable requirements, and the inspection specification rather than treated as identical across every industry.

A simplified way to understand them is:

The exact definition matters.

For example, a scratch that is considered minor on one product could be commercially unacceptable on another product if appearance is a major selling point.

Similarly, a functional failure should not automatically be treated as a minor issue simply because the physical defect looks small.

This is why buyers should define defect criteria before production and make sure the inspector is working from the same requirements as the factory.

What Do Ac and Re Mean in an Inspection Report?

Ac means Acceptance Number.

Re means Rejection Number.

They work together as the decision thresholds in the sampling plan.

For example, a report might show:

Major: Ac 7 / Re 8

This means that, under that particular sampling plan, a counted result of 7 major defects or fewer meets that acceptance criterion, while reaching 8 major defects reaches the rejection criterion.

It is not a statement that seven defects are generally acceptable for every order.

The Ac/Re values depend on the applicable sampling plan, sample size, AQL and other conditions.

That is why the following information should be read together:

Sample Size + Defect Class + AQL + Ac/Re + Actual Defect Count

Looking at only one of these numbers can lead to the wrong conclusion.

How to Read an AQL Inspection Result Step by Step

When you receive a China factory inspection report, do not jump directly to the final “PASS” or “FAIL.”

Read it in this order.

1. Check the lot size

First confirm what quantity the inspection represents.

If the factory says 5,000 units are finished but the inspection lot is recorded as 3,000 units, you should understand why the quantities differ.

The sampling result only has meaning in relation to the lot that was actually presented for inspection.

2. Check the sample size

Look at how many units were physically inspected.

Do not assume that a larger order automatically means a proportionally larger sample.

The sample size should correspond to the applicable sampling plan.

3. Check the inspection level and plan

If the report identifies an inspection level or sampling plan, confirm that it matches the agreed inspection instructions.

This becomes particularly important when different inspections use different sampling requirements.

4. Check the defect classification

Review the number of Critical, Major and Minor defects found.

Do not combine them into one total number without considering their classifications.

One major defect and several minor defects can have very different implications depending on the agreed acceptance criteria.

5. Check the AQL values

Confirm which AQL applies to each defect category.

A report might use different criteria for Major and Minor defects.

Do not assume that one AQL value applies to everything.

6. Check Ac and Re

Now compare the actual defect count with the applicable Ac/Re values.

For example:

*Illustrative example only. The AQL, sample size and Ac/Re values in an actual inspection must come from the applicable sampling plan and agreed inspection instructions.

The important point is not the specific numbers in this example.

The point is how to read the relationship:

Actual findings → compared with Ac/Re → acceptance or rejection decision.

7. Read the inspector's observations

Finally, read the detailed findings.

A report can technically meet its sampling acceptance criteria while still containing information that you need to investigate.

For example, the inspector may identify:

• Repeated cosmetic problems
• Inconsistent workmanship
• Packaging damage
• Incorrect labels
• Material differences
• Product dimensions close to the tolerance limit
• A problem concentrated in one production batch

The final decision should therefore consider the detailed findings, not only the large “PASS” label.

Does an AQL PASS Mean the Whole Order Is Good?

No.

An AQL PASS means that the sampled inspection results met the acceptance criteria of the applicable sampling plan.

It does not prove that every unit in the order is defect-free.

This is one of the most important points for overseas buyers to understand.

Sampling is used because checking every unit may be impractical or unnecessarily expensive. The trade-off is that the inspection provides evidence based on a sample rather than direct knowledge of every unit.

A passed sampling inspection therefore tells you something useful about the inspected lot, but it does not eliminate sampling risk.

It also does not prove that:

• Every carton was inspected
• Every unit is defect-free
• No defect exists outside the sample
• Production will remain unchanged after the inspection
• All future orders will have the same quality
• Every specification was tested unless it was included in the inspection scope

This distinction is especially important when deciding whether to release payment or shipment.

A buyer should understand what a passed inspection actually proves before treating the word “PASS” as a guarantee of the entire order.

What Should Buyers Check When the Result Is Close to the Limit?

A result that barely passes deserves more attention than a result that comfortably meets the agreed criteria.

Suppose the applicable Major criterion is Ac 7 / Re 8 and the inspector finds 7 major defects.

Technically, that result may meet the stated acceptance criterion.

But the buyer should still ask:

• What types of defects were found?
• Were the defects concentrated in one production batch?
• Are they repeated across different cartons?
• Are they related to the same production process?
• Could the same problem become worse after the inspection?
• Are the defects commercially important even if the sampling result passes?
• Does the buyer's own specification require additional action?

A “PASS” result is a decision under the sampling plan. It does not prevent the buyer from asking the factory to correct identified problems.

This is especially relevant when the inspection findings reveal a pattern rather than isolated defects.

A Simple Example of Reading an AQL Report

Imagine an overseas buyer has ordered a batch of finished consumer products from a Chinese factory.

The buyer requests a pre-shipment inspection after production is substantially complete.

The inspection report records:

• Lot size: 3,000 units
• Sample inspected: 125 units
• Major AQL: 2.5
• Minor AQL: 4.0
• Major defects found: 4
• Minor defects found: 6
• Critical defects found: 0
• Overall result: PASS

The buyer should not interpret this as:

“Only 3.2% of the entire order was inspected, so the factory has a 3.2% defect rate.”

That conclusion would be incorrect.

The 125 inspected units form the sample used by the applicable sampling plan. The defect counts are then compared with the corresponding acceptance criteria.

The correct questions are:

1. Was the correct lot presented?
2. Was the sample selected according to the agreed plan?
3. Were the defect classifications appropriate?
4. Were the actual findings below the relevant rejection thresholds?
5. What specific defects did the inspector record?
6. Does the buyer's product specification require any corrective action despite the PASS result?

This way of reading the report is much more useful than treating AQL as a simple percentage calculation.

Key Takeaways

• AQL is a parameter used in an acceptance sampling system; it is not simply the percentage of defects allowed in the whole order.
• Lot size, inspection level and the applicable sampling plan determine the sample size.
• AQL values such as 1.0, 1.5, 2.5 and 4.0 must be interpreted together with the sampling plan.
• Critical, Major and Minor defects are different classifications and should be defined according to the product and inspection requirements.
• Ac means Acceptance Number, while Re means Rejection Number.
• The actual defect count must be compared with the applicable Ac/Re criteria.
• An AQL PASS means the sampled result met the relevant acceptance criteria. It does not prove every unit in the lot is defect-free.
• A clear product specification remains necessary. AQL does not replace quality requirements.
• When a result is close to the acceptance limit, buyers should examine the actual defect findings instead of looking only at PASS or FAIL.
• The inspection report should be read as a combination of sampling information, defect evidence and acceptance criteria—not as a single number.

FAQ

Is AQL 2.5 the same as allowing 2.5% defective products?

No. AQL 2.5 should not be interpreted as a simple rule that 2.5% of the order may be defective. The applicable sampling plan determines the sample size and acceptance/rejection criteria.

Is a larger China factory order inspected with a proportionally larger sample?

Not necessarily. Sampling plans do not generally increase the sample size in direct proportion to the total lot size. The applicable lot-size range and inspection level determine the sample requirement.

What does Ac 7 / Re 8 mean?

Under that particular sampling criterion, 7 or fewer counted defects meet the acceptance threshold, while 8 reaches the rejection threshold. The actual Ac/Re values depend on the applicable sampling plan and should not be treated as universal numbers.

What is the difference between Major and Minor defects?

A Major defect has a more significant effect on function, performance, usability, appearance, or commercial acceptability than a Minor defect. The exact classification should come from the product-specific inspection requirements.

Can an AQL inspection PASS even when defects are found?

Yes. A sampling inspection can find defects and still pass when the counted findings remain within the applicable acceptance criteria.

Does an AQL PASS mean I should automatically ship the goods?

Not necessarily. Buyers should also review the detailed inspection findings, product specifications, packaging, quantities and any other requirements that were part of the inspection scope before making the shipment decision.

Should I use the same AQL settings for every China order?

Not automatically. The appropriate sampling and acceptance criteria depend on the product, buyer requirements, inspection procedure and risk considerations. The requirements should be agreed before the inspection rather than changed after seeing the result.

Need an AQL Inspection in China?

If you need someone in China to carry out an inspection according to your specifications, sampling requirements and agreed inspection scope, local inspection support in China can help with the on-site work and communication with the factory.

Send us the product type, factory location, order quantity, production status and what you need checked. You can contact our team with the details and we can discuss the practical inspection requirements before arranging the visit.