Quality

AQL Inspection for Custom Socks: Defects and Sampling

Published: 2026-06-17By ZheSock TeamReading time: 5 min

A sock AQL inspection decides whether a finished lot can ship, needs sorting, or must stay on hold. The real control starts earlier. Buyers and factories need written defect rules, size tolerances, packaging standards, and AQL levels before bulk knitting starts. On a 20,000 pair order, one repeated fault, such as a logo 8 mm too low or an open toe seam, can cause days of sorting and hundreds of dollars in rework.

Table of Contents

1. What does sock AQL inspection mean for buyers?
2. Which sock defects are critical, major, or minor?
3. How many pairs are sampled during sock AQL inspection?
4. When should inspection happen in the sock production timeline?
5. What measurements should inspectors check?
6. How can buyers reduce failed AQL results?

What does sock AQL inspection mean for buyers?

Sock AQL inspection is a final random check of a finished production lot against an agreed Acceptable Quality Limit. Many buyers use ISO 2859 tables as the reference. For socks, the check usually happens after knitting, toe linking, boarding, pairing, labeling, and carton packing.

A common setup is General Inspection Level II, AQL 2.5 for major defects, AQL 4.0 for minor defects, and zero acceptance for critical defects. For example, an 8,000 pair lot under General II usually gives code letter L and a 200 pair sample. At AQL 2.5, the lot passes with 10 or fewer major defects and fails at 11. At AQL 4.0, it passes with 14 or fewer minor defects and fails at 15.

AQL does not mean 2.5 percent of the order can be bad. That is a common mistake. AQL is a sampling rule. The inspector checks a set number of pairs, counts defects by class, then compares the counts with the accept and reject numbers in the table.

Which sock defects are critical, major, or minor?

Defect grading must be written before production. If the buyer only says "good quality," the factory and inspector may judge the same sock in different ways. A clear defect list cuts arguments when cartons are opened.

Critical defects: needle pieces, metal contamination, mold, live insects, sharp objects inside packaging, wrong fiber content label, missing CE mark when CE applies to the product type.
Major defects: hole larger than 2 mm, open toe seam over 5 mm, broken elastic, wrong size, wrong logo, barcode not scannable, pair length outside tolerance, heavy shade mismatch between left and right sock, dirty mark over 5 mm on a visible area.
Minor defects: loose yarn tail under 10 mm, small slub under 3 mm, light oil mark under 3 mm on a hidden area, carton print shifted under 10 mm, label fold that does not cover the barcode or size.

Logo rules need extra detail. A 96 needle sock cannot show fine text well. A 144 needle jacquard logo is common for casual and sport socks. A 168 needle sock gives cleaner edges for small artwork, but thin lines under 1.5 mm may still break after knitting. Set the pass rule from the approved pre production sample, not from the flat artwork file.

How many pairs are sampled during sock AQL inspection?

Sample size depends on lot quantity and inspection level. Most importers use General II for final inspection. Level I reduces inspection time but gives less confidence. Level III checks more pairs and suits first orders, strict retail programs, or goods with past failure records.

Typical General II sample sizes are clear. A 500 pair lot gives 50 sample pairs. A 1,200 pair lot gives 80 sample pairs. A 5,000 pair lot gives 200 sample pairs. A 35,000 pair lot gives 315 sample pairs. At AQL 2.5, a 200 pair sample passes with 10 or fewer major defects and fails at 11. A 315 pair sample passes with 14 or fewer major defects and fails at 15.

Sampling must be random across cartons, colors, sizes, and SKUs. If the shipment has 80 cartons, the inspector should draw from at least the square root of the carton count, rounded up, so 9 cartons or more. For mixed size runs, the sample should reflect the size ratio. Do not pick only cartons near the loading door. Pull from the door area, the middle stack, and the back wall.

When should inspection happen in the sock production timeline?

Final sock AQL inspection should happen when at least 80 percent of the order is packed and the balance is finished. Some buyers ask for 100 percent packed inspection. That gives cleaner sampling, but it can add 2 to 4 days if the lot needs sorting. For new styles, an inline check is cheaper than finding the same defect in sealed cartons.

A normal custom sock timeline is 2 to 5 days for artwork adjustment, 5 to 7 days for sampling, and 15 to 25 days for bulk production after sample approval for 3,000 to 10,000 pairs. Custom dyed yarn can add 5 to 10 days. Final inspection usually needs 1 working day on site and 1 working day for the written report with photos, defect counts, carton numbers, and measurement results.

At ZheSock in Datang, Zhejiang, MOQ can start at 100 pairs for some custom sock styles. Formal AQL is more useful from about 1,000 pairs upward because the sample can represent the shipment better. For small runs of 100 to 300 pairs, a 20 percent check or full check on size, logo, and pairing often gives better control than a standard AQL sampling plan.

What measurements should inspectors check?

Visual checking is not enough. A proper sock AQL inspection also checks size, stretch, weight, logo position, and packing. The buyer should provide a spec sheet with tolerances. Without it, the inspector can only compare bulk goods with the approved sample. That is weaker.

Common checkpoints include foot length, leg height, welt width, sole width, cuff stretch, pair weight, logo height from heel, logo distance from welt, hangtag position, barcode, polybag quantity, and carton assortment. For crew socks, foot length tolerance is often plus or minus 0.5 cm. Leg height is often plus or minus 1.0 cm. Pair weight tolerance is often plus or minus 5 percent. Logo position should usually stay within plus or minus 0.5 cm from the approved sample.

Construction changes the pass standard. A 96 needle sock usually has a thicker look and less detail. A 144 needle sock is common for daily wear and sport socks. A 168 needle sock is better for smaller logos. A 200 needle dress sock can use finer yarn and a smoother hand feel. Typical cotton blend crew socks may run 45 to 75 GSM by pair area equivalent. Terry sport socks often feel heavier because loop yarn adds bulk and weight.

How can buyers reduce failed AQL results?

The best way to reduce failed inspection is to freeze the product file before yarn purchase. That file should include yarn composition, Pantone references, knit needle count, size table, artwork file, approved sample photos, packaging layout, carton marks, barcode file, AQL levels, and defect grading. One missing detail can create a full lot dispute.

During bulk production, ask for inline checks instead of only final photos. On a 10,000 pair order, the factory should check the first 30 to 50 pairs per color after machine setup, then recheck after toe linking and boarding. Cuff stretch, logo height, and foot length should be recorded against the spec sheet. Boarding temperature and time matter too. Overboarding can stretch socks beyond tolerance, while low heat can leave twisted legs and poor shape.

Cost matters. Basic cotton blend custom socks at medium volume often sit around USD 0.70 to USD 1.40 per pair. Terry sport socks may run USD 1.20 to USD 2.50 per pair. Compression socks, merino blends, or GRS yarn can cost more. ZheSock works with OEKO-TEX certified materials on request and uses inline QC before final inspection, so defect rules become production checks instead of late paperwork.

Frequently Asked Questions

What AQL level is common for custom socks?

Many buyers use AQL 2.5 for major defects and AQL 4.0 for minor defects, with zero acceptance for critical defects. Premium retail programs may use AQL 1.5 for major defects. A stricter level increases the chance of failure and sorting cost, so it should match the price point, sales channel, and defect risk.

Can a small sock order use AQL inspection?

Yes, but standard AQL is less useful on very small orders. For 100 to 300 pairs, check 20 percent or inspect all pairs for size, logo, pairing, and obvious holes. From about 1,000 pairs upward, a normal AQL sample gives a better read on the lot.

Who should define sock defects before production?

The buyer and factory should agree on defect rules after sample approval and before bulk yarn purchase. The list should define critical, major, and minor defects. It should also state size tolerance, logo tolerance, packaging rules, carton assortment, barcode requirements, and the approved reference sample.

Does AQL inspection replace factory quality control?

No. AQL is a shipment decision tool. Factory QC still needs to check yarn, knitting, toe closing, boarding, pairing, labeling, metal control, and carton packing. If the first serious check happens at final inspection, sorting can add 2 to 5 days and may miss the vessel date.

What happens if a sock shipment fails AQL?

The usual options are sorting, repair, replacement, price adjustment, or rejection. Holes, wrong logos, open toe seams, and wrong sizes usually need sorting or remake. Minor packaging issues may be accepted only with written buyer approval. The inspection report should show photos, defect counts, sample size, AQL result, and carton locations.

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