What Is AQL Inspection? A Plain-English Guide for Amazon Sellers

AQL inspection is a way to judge a whole production lot by checking a random sample of it. AQL stands for Acceptance Quality Limit. You pick a lot size, an inspection level and an AQL value for each defect type, and a standard sampling table tells you how many units to inspect and how many defects are allowed. If the number of defects found is at or below the accept number, the lot passes. If it reaches the reject number, the lot fails. For many consumer products sold on Amazon, a common setup is General Inspection Level II with 0 critical, 2.5 major and 4.0 minor.

The method sounds technical, but once you see one worked example it makes sense.

Where the Tables Come From

AQL sampling uses published standards. The two you will see most are:

• ISO 2859-1, the international standard for sampling by attributes
• ANSI/ASQ Z1.4, the American standard, which uses essentially the same tables

Inspection companies and factories use these tables so that buyer and supplier agree in advance on what “pass” means. That removes a lot of arguing after the fact.

The Three Inputs

1. Lot size

The lot is the total quantity of the order (or the batch being inspected). Bigger lots need bigger samples, but not proportionally bigger. That is the efficiency of sampling.

2. Inspection level

Inspection levels control how large the sample is for a given lot size. General Inspection Level II is the default for most consumer goods. Level I uses smaller samples, Level III larger ones. There are also special levels (S-1 to S-4) with very small samples, typically used for tests that are slow or destroy the product.

3. AQL value per defect class

Defects are usually sorted into three classes:

Defect class	Meaning	Example	Typical AQL choice
Critical	Could cause harm or breaks a legal or safety requirement	Sharp edge on a toy, exposed wiring	0 (no critical defects accepted)
Major	Likely to cause a return or make the product fail its purpose	Zip does not close, wrong color, missing part	2.5
Minor	Cosmetic issue that probably will not stop the sale	Small loose thread, faint mark	4.0

These values are common choices, not rules. A brand with a premium product might set major at 1.5 or 1.0. A low-cost item might use a looser minor value. What matters is that you agree on the values with your supplier before production.

A note on critical defects: 0 is not a value printed in the standard tables. In practice it is a buyer policy that says any critical defect found fails the lot.

How Sample Size Depends on Lot Size

Using the standard table, you first find a sample size code letter from the lot size and inspection level, then read the sample size and accept/reject numbers for your AQL from the master table.

Worked example

Say you ordered 5,000 units and inspect at General Inspection Level II.

1. A lot of 3,201 to 10,000 units at Level II gives code letter L.
2. Code letter L means a sample size of 200 units.
3. At AQL 2.5 (major defects), the accept/reject numbers are 10/11. If 10 or fewer major defects are found in the 200 units, that part passes. If 11 or more are found, the lot fails.
4. At AQL 4.0 (minor defects), the accept/reject numbers are 14/15. Up to 14 minor defects pass, 15 or more fail.
5. For critical defects at 0, a single critical defect fails the lot.

Each defect class is judged separately. A lot can be fine on minor defects but fail on major ones, and the overall result is a fail.

Notice what the example means in practice: inspecting 200 units out of 5,000 is 4% of the lot, yet the sample is chosen by a recognised statistical method. AQL does not promise zero defects in the lot. It gives you a known, agreed level of risk.

What Gets Checked

A typical AQL inspection report covers:

• Quantity and packing: total cartons, units per carton, carton marks, inner packing
• Workmanship: visual defects sorted into critical, major and minor
• Specifications: dimensions, weight, color, materials against your spec sheet and golden sample
• Function tests: does it switch on, open, close, fit
• Labels and barcodes: correct FNSKU or product barcode, scannable, correct position
• Special checks: for example a carton drop test or a moisture reading, if agreed

Amazon sellers should include label and packaging checks, because a wrong or unscannable barcode causes problems at the fulfillment center even when the product itself is perfect.

When to Inspect

The most common timing is a pre-shipment inspection: production is complete and most of the goods (often stated as at least 80%) are packed in their export cartons. The inspector picks cartons at random and draws the sample from them. This timing lets you see finished, packed goods, and it happens before you pay the balance, so you still have leverage to ask for rework.

Other options are useful for higher-risk orders:

• During production inspection, when part of the order is finished, to catch problems early
• Container loading check, to confirm the right goods and quantity go into the container

AQL vs 100% Inspection

AQL is a sampling method. It is efficient and standard, but some orders justify checking every unit, for example when a lot has failed AQL and been reworked, when a defect is known to occur randomly, or when the product is high value. 100% inspection costs more time but sorts out every defective unit instead of just measuring the defect rate.

Frequently Asked Questions

Does passing AQL mean there are no defects?

No. Passing means the number of defects in the sample was within the agreed limits. Some defective units may still be in the lot. If that is not acceptable, use a stricter AQL or 100% inspection.

Which AQL should I use for Amazon products?

Many sellers start with 0 critical, 2.5 major and 4.0 minor at General Inspection Level II, then tighten the values for products where returns or reviews are sensitive. Agree the values with your supplier in writing before production.

What happens if a lot fails?

Usually the supplier sorts and reworks the goods, and a re-inspection is done. Your contract should say who pays for re-inspection and what happens if the lot fails again.

Who should define the defect list?

You should, with input from your supplier or inspector. A clear defect list with photos and your golden sample makes results consistent and avoids disputes.

How We Can Help

At our facility in Longhua, Shenzhen, we inspect goods in-house at three levels: a receiving check, AQL sampling, and 100% inspection. See our quality inspection service. If your goods are still at the supplier, we can carry out a pre-shipment inspection at their factory through our factory audit and inspection service.