AQL Sampling Explained: AQL Inspection for Apparel

AQL sampling decides whether a production order passes inspection. Here is what AQL 2.5 and 4.0 mean, how to read an AQL table, sample sizes for typical apparel orders, and how garment defects are classified.

What AQL Means

AQL stands for acceptance quality limit, still widely called acceptable quality level. It is the defect rate a buyer is prepared to tolerate in a production lot, expressed as a percentage, and it is the setting that decides how a pre-shipment inspection reaches a pass or fail verdict.

AQL sampling is the method behind that verdict. Instead of checking every garment in an order, an inspector pulls a random sample of a size set by the order quantity, examines each unit against the approved sample and the specification, counts the defects, and compares the count with an acceptance number from a published table. At or below the acceptance number, the lot passes. At or above the rejection number, it fails.

The tables come from ISO 2859-1, the international standard for sampling by attributes, and from ANSI/ASQ Z1.4, its American counterpart. The two use the same sample size code letters, sample sizes and acceptance numbers for the plans most buyers use, so an AQL report from a factory in Turkey, Portugal or Vietnam reads the same way.

This guide explains what AQL numbers mean, how to read an AQL table, what sample sizes look like for real apparel order quantities, how defects are classified on garments, and what to agree with a manufacturer before the inspection rather than after it. It is written for private label and DTC brands placing a first or early production run, whether through a factory you found yourself or a sourcing partner such as SourceBridge, which works with clothing and home-textile manufacturers in Turkey.

Why AQL Matters When You Order Clothing Production

A production order is the point where a brand stops paying for samples and starts paying for inventory. Once goods have left the factory, a defect costs freight, duty and warehouse handling on top of the garment itself, and for an Amazon seller it can also cost returns, reviews and a listing's standing. Finding the problem while the order is still in the factory, where it can be sorted, reworked or remade, is far cheaper than finding it at your warehouse.

AQL gives both sides a shared, written rule for that moment. Without it, a pre-shipment inspection is an opinion. With it, the factory knows before production starts how the goods will be judged, the inspector knows how many units to pull and what counts as a failure, and the brand has a documented basis for asking for rework instead of an argument.

It also keeps inspection proportionate. Checking every unit of a 3,000-piece order is slow and expensive; checking 125 units chosen at random gives a statistically grounded picture of the whole lot in a fraction of the time.

What the AQL Numbers Mean

AQL values run in a fixed series: 0.065, 0.10, 0.15, 0.25, 0.40, 0.65, 1.0, 1.5, 2.5, 4.0, 6.5 and higher. Lower numbers are stricter.

An AQL of 2.5 means that a production lot with a defect rate of around 2.5 percent or better will be accepted most of the time. It does not mean the shipment is guaranteed to contain no more than 2.5 percent defective units, and it does not mean that 2.5 percent of the sample may be defective. A sample gives you a probability, not a certainty: a lot that is slightly worse than the limit can pass by chance, and a lot that is slightly better can occasionally fail.

In practice, buyers set a different AQL for each class of defect:

Critical defects: most buyers accept none. A single critical defect in the sample fails the lot.

Major defects: 2.5 is the most common setting for consumer apparel and home textiles. Brands with a higher price point or a strict returns profile often use 1.5 or 1.0.

Minor defects: 4.0 is the most common setting.

These are common starting points, not rules. The right setting depends on the product, the price point and how much a defect costs you once it reaches a customer.

How AQL Sampling Works: Lot Size, Inspection Level and Sample Size

An AQL inspection plan is built from three inputs: the lot size, the inspection level and the AQL itself.

The lot size is the quantity being inspected. For a single-style order it is usually the full order quantity. For an order with several styles or colourways, agree in writing whether the whole shipment is one lot or each style is inspected as its own lot, because that changes the sample size.

The inspection level sets how large the sample is relative to the lot. ISO 2859-1 defines three general levels and four special levels:

General Inspection Level II is the default and the one used in most apparel inspections.

Level I uses a smaller sample and is sometimes used for repeat orders from a factory with a good record.

Level III uses a larger sample, for a new factory, a product with a history of problems or a high-value order.

Special levels S-1 to S-4 use very small samples. They are used for checks that are slow or destructive, such as measuring garments against the size chart or testing a carton, not for the general visual check.

The sample size then follows from the lot size and the inspection level, and the AQL gives the acceptance and rejection numbers for that sample.

How to Read an AQL Table

Reading an AQL chart takes two steps.

Step one: find the sample size code letter. The first table lists lot size ranges down the side and inspection levels across the top. Find your lot size, read across to your inspection level, and note the letter. At General Inspection Level II, a lot of 281 to 500 units is letter H; 501 to 1,200 is J; 1,201 to 3,200 is K; 3,201 to 10,000 is L.

Step two: find the sample size and the acceptance numbers. The second table lists the code letters down the side, each with its sample size, and the AQL values across the top. Letter H means a sample of 50 units, J means 80, K means 125 and L means 200. Read across from the letter to the AQL column you chose. The cell gives two numbers: Ac, the acceptance number, which is the highest defect count at which the lot still passes, and Re, the rejection number, at which it fails.

Some cells contain an arrow instead of numbers. An arrow means there is no plan for that combination; follow the arrow to the first cell that has numbers and use that cell's sample size as well as its Ac and Re.

The values in this guide are for single sampling under normal inspection, which is what a standard pre-shipment inspection uses. ISO 2859-1 also defines tightened and reduced inspection, with switching rules for moving between them based on a supplier's recent results.

AQL Sample Sizes for Typical Apparel Orders

These worked examples use General Inspection Level II, single sampling, normal inspection, with the common settings of 2.5 for major defects and 4.0 for minor defects.

300 units (letter H): sample 50 units. Major defects: accept up to 3, reject at 4. Minor defects: accept up to 5, reject at 6.

1,000 units (letter J): sample 80 units. Major: accept up to 5, reject at 6. Minor: accept up to 7, reject at 8.

3,000 units (letter K): sample 125 units. Major: accept up to 7, reject at 8. Minor: accept up to 10, reject at 11.

5,000 units (letter L): sample 200 units. Major: accept up to 10, reject at 11. Minor: accept up to 14, reject at 15.

Majors and minors are counted and judged separately. A lot fails if either count reaches its rejection number, and it fails on any critical defect.

Two practical points follow from the table. First, the sample does not grow in step with the order: 300 units means a 50-piece sample, 3,000 units only 125. Second, on a small first order a handful of defects decides the result, which is one more reason to settle the defect definitions before production rather than during the inspection.

How Defects Are Classified on Garments

The classification of a defect matters as much as the AQL. A loose thread counted as a major defect fails lots that should pass; a wrong size label counted as minor passes lots that should fail. Write the classification into the purchase order or the inspection checklist. Typical apparel examples:

Critical: anything that makes the product unsafe or illegal to sell. A broken needle or sharp metal fragment in the garment; small parts that can detach from baby or children's clothing; drawstrings at the hood or neck of children's upper outerwear, which US regulators treat as a substantial product hazard.

Major: a defect a customer would likely return the product for. Open seams, holes, broken stitching at stress points, measurements outside the agreed tolerance, visible shade differences between panels, misplaced or crooked prints and embroidery, wrong or missing size, care or fibre-content labels, a faulty zip or fastener.

Minor: a defect that falls short of the specification but would not usually lead to a return. Untrimmed thread ends, slight unevenness in stitching on a non-visible area, a small mark that comes out with normal handling.

Agree, too, whether the inspector counts defects or defective units. A garment with three separate faults can be recorded as three defects or as one defective unit, and the two approaches give different results against the same acceptance number.

What a Garment AQL Inspection Checks

The AQL count covers the visual workmanship check on the sample. A full pre-shipment inspection for apparel also includes checks that are not counted against the AQL in the same way:

Quantity and packing. Units produced and packed against the order, the size and colour breakdown, and the number of finished cartons.

Conformity to the approved sample. Style, fabric, colour, trims, print and embroidery placement, compared with the approved pre-production sample and the tech pack.

Measurements. Key points of measure on a smaller sample from each size, against the size chart and its tolerances, usually under a special inspection level.

Fabric weight and hand feel. A GSM check from several cartons against the agreed tolerance, as described in what GSM means in fabric.

Labelling. Care, fibre content and country of origin labels, which US rules require on most apparel, plus brand labels, hangtags and barcodes. For Amazon FBA, each unit's barcode should scan correctly and cartons should match Amazon's labelling and packaging requirements.

Packaging and cartons. Folding, polybags and warning text, carton marks, carton dimensions and weight, and, where agreed, a carton drop test.

When to Inspect: Before, During and After Production

AQL sampling is most often applied at the final stage, but an order can be checked at several points:

Pre-production check. Fabric, trims and the first production cut are checked against the approved sample before sewing starts. Problems here cost the least to fix.

During production. Once the first finished units are off the line, an inspector checks them so that a recurring fault is corrected while most of the order has not yet been sewn.

Pre-shipment inspection, also called final random inspection. Carried out when production is finished and commonly at least 80 percent of the order is packed, so that the sample can be drawn at random from finished cartons. This is where the AQL verdict is given.

For a first order from a new factory, a during-production check alongside the pre-shipment inspection is worth considering. For a repeat order of an established style, a pre-shipment inspection alone is common.

What Happens When a Lot Fails

A failed AQL inspection is not the end of the order. It is a documented reason to act before shipment. The usual options are:

Sort and rework. The factory checks every unit, repairs or replaces defective pieces, and the lot is inspected again.

Accept with a concession. If the defects are cosmetic and the timeline matters, the buyer may accept the lot with a price adjustment or replacement units, agreed in writing.

Reject. For critical defects, or failures that cannot be reworked, the buyer can refuse the lot under the terms of the purchase order.

Agree in advance who pays for a re-inspection and how much time the factory has to rework. Payment terms that hold the balance until after a passed inspection give both sides a clear reason to settle a failure quickly.

What to Agree With Your Manufacturer Before Production

An AQL inspection works when the standard is settled before the goods exist. Put these points in writing with the purchase order:

The standard (ISO 2859-1 or ANSI/ASQ Z1.4), the inspection level and the AQL for critical, major and minor defects.

The defect classification list for the product, and whether defects or defective units are counted.

The reference: the approved pre-production sample and the final tech pack, including measurement tolerances.

Whether the lot is the full order or each style, and when the inspection takes place.

Who carries out the inspection: the factory's own QC team, the buyer, a third-party inspection company or the sourcing partner.

What happens after a failure: rework time, re-inspection cost and the effect on payment.

These points belong in the same conversation as minimum order quantity, sampling and lead time. The guide to how to find a clothing manufacturer covers the questions to ask before a sample, and the landed cost calculator includes a line for pre-shipment inspection when you compare origins.

How SourceBridge Handles Inspection

SourceBridge works with clothing and home-textile manufacturers in Turkey for private label and Amazon brands, with a minimum order quantity of 300 units per style for most textile products. Production follow-up is part of the service: once the sample is approved, SourceBridge oversees production and carries out a pre-shipment inspection at the factory, comparing the finished goods against the approved sample. Buyers receive photo documentation and AQL inspection reports before goods ship.

If you are preparing a first production order and want the inspection standard agreed at the quoting stage, see textile sourcing or read clothing manufacturers for startups for how small first orders are structured.

FAQ: AQL Sampling and Inspection

What does an AQL of 2.5 mean?

It means a production lot with a defect rate of around 2.5 percent or better will be accepted most of the time. In an inspection it sets the acceptance number for the sample: for a 3,000-unit order inspected at General Inspection Level II, an AQL of 2.5 means a sample of 125 units with up to 7 major defects accepted and 8 rejected. It is the most common setting for major defects in consumer apparel.

What does an AQL of 4.0 mean?

AQL 4.0 is a looser limit, most often used for minor defects. For a 3,000-unit order at General Inspection Level II, it means up to 10 minor defects are accepted in the 125-unit sample and 11 fail the lot.

What does an AQL of 1.0 mean?

AQL 1.0 is a stricter limit than 2.5, used for major defects by brands with a higher price point or a low tolerance for returns. For a 3,000-unit order at General Inspection Level II, the sample is still 125 units, but only up to 3 major defects are accepted and 4 fail the lot.

How do you read an AQL chart?

Use two tables. In the first, find your lot size and read across to your inspection level, usually General Inspection Level II, to get a sample size code letter. In the second, find that letter to get the sample size, then read across to your AQL column for the acceptance number (Ac) and rejection number (Re). If the cell shows an arrow, follow it to the first cell with numbers and use that cell's sample size.

What is the difference between AQL sampling and 100 percent inspection?

AQL sampling checks a random sample and judges the whole lot from it, which is faster and cheaper and is the normal method for pre-shipment inspection. A 100 percent inspection checks every unit. It is used for critical items, for very small orders, or to sort a lot after it has failed an AQL inspection.

What AQL should I use for clothing?

A common starting point for consumer apparel is zero critical defects, 2.5 for major defects and 4.0 for minor defects, at General Inspection Level II. Brands with a higher price point or strict return thresholds often tighten majors to 1.5 or 1.0. Agree the setting with the manufacturer before production.

How many pieces are inspected in an AQL inspection?

It depends on the lot size and inspection level. At General Inspection Level II, an order of 300 units gives a sample of 50, 1,000 units a sample of 80, 3,000 units a sample of 125, and 5,000 units a sample of 200.

Who carries out an AQL inspection?

The factory's own QC team, the buyer's staff, a third-party inspection company or a sourcing partner. What matters is that the inspector works to the AQL, defect list and reference sample agreed with the factory before production, and that you receive the report with photographs before the goods ship.

AQL Sampling Explained: How AQL Inspection Works for Clothing Orders