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Acceptable Quality Limit (AQL) Used for Quality Inspections

The demand for more accurate and efficient products increases as the world progresses. Various industries are taking drastic steps in manufacturing their products to meet this demand. They aim to ensure product quality and produce accurate and reliable products. However, they must go through the necessary quality tests to ensure product reliability. And one of the most common quality inspection procedures in this situation is AQL (Acceptable Quality Limit).

This method is important in product manufacturing. Therefore, it is crucial to understand this critical term and its uses in real-life applications. However, this article discusses AQL’s fundamentals. Besides, it also navigates to a quick AQL calculator that might be helpful for immediate product data.

1. What is AQL Table?

AQL usually stands for Acceptable Quality Limit. It is a method for checking random samples from production.

AQL table is a chart that lists the number of acceptable items based on the different batch or lot sizes. AQL tables verify that the products have an acceptable quality that meets customers’ expectations. However, the rejected collection is returned to production for further inspection.

1.1 AQL Table A – Sample Size Code Letters

The following table includes different lots or batch sizes on the left side. And on the table’s right side, various sample size code letters are based on the inspection level.

The Special Inspection Level is used instead of the general inspection level when the production has to be special operationally inspected.


– The General Sampling Level may be chosen between I, II, or III.
The default General Sampling Quality Level in PORTMAN is II.

– Special inspection standards including S1, S2, S3 and S4.
The default Special Sampling Quality Level in PORTMAN is S2, for weight checking, size checking, technical testing, etc..

1.2 AQL Table B – Single Sampling Plans for Normal Inspection

Based on the previous table, you can decide the appropriate value from the following table. However, in Table II, the leftmost column determines the type of sample you chose from Table 1. The second column defines the number of product samples for a specific lot or batch.


The regulatory agency or customer determines acceptable quantity levels in this situation. Generally, it starts from 0.10 to 6.5; in most cases, it ranges from 1.0 to 4.0. According to the table.

“Ac” stands for acceptance numbers.

“Re” stands for rejection numbers.

The sampling AQL table is prevalent in manufacturing and quality control settings. Typically, the AQL level is determined by the customer or regulatory agency. The manufacturer uses statistical sampling to determine whether the batch or lot meets the AQL level. The AQL sampling table or AQL method is necessary for several reasons:

– Ensuring Product Quality:

AQL ensures that product quality meets the required standards. By setting an AQL, manufacturers can determine the maximum number of defective items acceptable in a batch.

– Reducing Inspection Costs:

Inspecting every item is time-consuming and costly. In this case, AQL tables can save time and decrease inspection costs.

– Optimized Production:

AQL method can optimize production processes to minimize defects. It also helps reduce waste, improve efficiency, and increase customer satisfaction.

– Meeting Regulatory Requirements:

Many industries or customers specify the maximum allowable defect levels. Sampling the AQL table helps manufacturers to comply with these requirements. As a result, it avoids regulatory penalties.

– Facilitating International Trade:

This method is a globally recognized quality control standard. As a result, manufacturers can use the AQL sampling table to ensure their products meet quality requirements.

2. How to Use the AQL Tables in Quality Inspection

The AQL tables typically determine whether a batch of products meets specific quality standards. Here are three primary steps on how to use the AQL tables in quality inspection:

Step 1: Determine the appropriate sample size and AQL level

Before using the AQL table, it is essential to determine the appropriate sample size and AQL level. The number of items that can be defective in the batch without being rejected depends on the sample size and AQL level.

Step 2: Define defects based on the severity

You can determine the number of defects in the samples at this stage. In this case, the following three are the primary defects that you can classify.

· Critical Defects:

Critical defects are likely to result in severe harm or injury to the user, such as sharp edges or electrical hazards.

The default Critical Defect AQL in PORTMAN is 0.

· Major Defects:

Major defects are likely to result in the product’s failure to meet its intended use. For example, missing components or incorrect labeling are considered in this case.

The default Major Defect AQL in PORTMAN is 2.5.

· Minor Defects:

Minor Defects, such as minor scratches or surface blemishes, do not affect the product’s function or usability.

The default Minor Defect AQL in PORTMAN is 4.0.

Step 3: Use the AQL table to determine the acceptability

Finally, when you have classified the defects, you can use the AQL table to determine whether the batch meets an acceptable quality level. The lot may be rejected if the defects exceed the allowable limit.

For Example:

Suppose a customer specifies an AQL level of 1.5% for a batch of 1000 Bluetooth Speaker order, Choose Gerneral inspection levels II and AQL Level 1.5. so:

Sample size code letter = J

Sample size code = 80

Ac = 3, Re = 4

Target: Critical Defects = 0, Major Defects ≤ 4, Minor Defects ≤ 3.

If the final quality spot check result is better or not worse than this result, then the quality inspection of this batch of goods is passed.

This video describes AQL table in detail and how to use it. It can be collected and watched.

3. More Info about AQL Tables (General inspection Levels vs. Special inspection levels)

Typically there are two types of inspection levels found in the AQL tables. These two AQL levels are general inspection levels and special inspection levels.

General inspection levels are widely popular for routine inspections of products. It depends on the size and the desired assessment level (regular, reduced, or tightened). However, this inspection level is the default option.

On the other hand, special inspection levels are prevalent for non-routine inspections. It is essential, especially for high-value or critical products. This inspection level typically depends on a fixed sample size. It requires a larger sample size and more stringent acceptance criteria.

Above all, AQL tables are based on international standards, such as ISO 2859-1 and ANSI/ASQ Z1.4. It provides a helpful tool for ensuring consistent and reliable quality control in manufacturing.

4. Suggestionson AQL Levels

Here are some of the most beneficial suggestions for working with AQL levels.

Tip 1. Specific requirements of the product andthe customer’s quality level determinethe AQL levels.

Tip 2. Consider the type of defect and its severity.

Tip 3. Consult industry standards and quality experts about the AQL levels appropriate for your product.

Tip 4. Lower AQL levels are appropriate for products with high safety or regulatory requirements. However, higher AQL levels may be suitable for less critical products.

Tip 5. Re-evaluate the AQL level periodically.

Tip 6. Use the AQL calculator to ensure consistent and reliable quality control.

5. AQL Calculator Acceptable Quality Limit

AQL calculator is a tool that quickly determines the appropriate sample size and acceptance or rejection values. It works based on the AQL levels desired by the user. AQl calculator is fast to decide on the results. However, the AQL calculator is widely available online. It can be a helpful tool for ensuring consistent and reliable quality control.

6. FAQ

#1 Why Use AQL Rather Than Inspect 100% of Products?

AQL method saves manufacturers time and money by inspecting only a few samples from the whole batch. This method is more efficient, faster, and reliable and follows international standards. As a result, it became the most accepted method of inspection.

#2 Can Quality Inspection with AQL Table Guarantee that My Goods Have Zero Defects?

No. This statistical sampling method assesses the quality of a batch of products based on sample size. However, it provides a high level of confidence but can not eliminate the possibility of some defects in the collection.

#3 What Should I do If The Goods Fail to Pass The AQL Table Standard and The Loss is Relatively Significant When I Reject The Goods?

Negotiating with the supplier to find a mutually acceptable solution would be best. You can request a rework of the goods, a partial refund, or a discount on future orders. However, you can also weigh the cost of accepting defective goods against the potential damage to your brand’s reputation.

Joey Gan
Article by:
Joey Gan
The Co-founder of Ruizhi Sourcing. With 10 years of experience in the field of sourcing in China, we help 1k+ clients import from China and customize new products.. Contact with me at Linkedin
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