Quality

Custom Sock AQL Inspection: Defects and Sample Size

Published: 2026-07-02By ZheSock TeamReading time: 5 min

Sock AQL inspection is the buyer's last statistical check before a custom sock shipment leaves the factory. It does not inspect every pair. It pulls a fixed sample from the finished lot and applies agreed pass or fail limits. For a 3,000 pair order, that often means 125 pairs checked under ANSI/ASQ Z1.4, General Inspection Level II. The result shows whether the lot can ship, needs sorting, or needs rework before cartons move.

Table of Contents

1. What does sock AQL inspection mean?
2. Which sock defects are critical, major, or minor?
3. How many pairs should be checked by AQL sample size?
4. When should inspection happen during sock production?
5. What measurements should a sock inspector record?
6. How should buyers write AQL terms into the purchase order?

What does sock AQL inspection mean?

Sock AQL inspection means checking a production lot by sample size, not by 100 percent sorting. Most importers use ANSI/ASQ Z1.4, normal inspection, General Inspection Level II. A common sock setting is Critical 0, Major 2.5, Minor 4.0. Critical 0 means one critical defect fails the lot.

Here is a typical example. A finished lot of 2,000 pairs usually uses code letter K under General Level II, so 125 pairs are inspected. At AQL 2.5 for major defects, 7 major defects pass and 8 fail. At AQL 4.0 for minor defects, 10 minor defects pass and 11 fail. Put these numbers in the purchase order before knitting starts.

AQL is not a quality promise. It is a decision rule. It works only when the sample is pulled at random from sealed cartons and the defect classes are agreed in writing before bulk production.

Which sock defects are critical, major, or minor?

Defect grading decides the result. The same physical issue can get a different grade depending on placement and buyer risk. A loose yarn end inside the cuff is often minor. A hole at the toe is major. A sharp metal fragment in a carton is critical.

Critical defects: mold, blood stain, sharp metal, insect contamination, wrong fiber claim on the legal label.
Major defects: hole, broken elastic, wrong size packed, wrong color packed, missing barcode, unreadable care label, poor toe closing, heavy shade difference, logo placed more than 1 cm outside spec.
Minor defects: loose yarn end under 2 cm, light oil mark under 3 mm, small carton dent, slight knitting line not visible when worn.

For branded socks, logo errors often count as major when they affect the front view, side view, or retail pack. A jacquard logo shifted by 15 mm can trigger a retail complaint even when the sock still fits.

How many pairs should be checked by AQL sample size?

Sample size follows the lot quantity. It does not follow the buyer's budget. Under ANSI/ASQ Z1.4, General Inspection Level II, common sock sample sizes are 50 pairs for a 500 pair lot, 80 pairs for a 1,000 pair lot, 125 pairs for a 3,000 pair lot, and 200 pairs for a 10,000 pair lot.

For mixed orders, the inspector must pull across colors, sizes, and cartons. If the order has black, white, and navy socks in S, M, and L, the sample cannot come from one carton of medium black socks. For a 3,000 pair order packed in 60 cartons, a practical plan is to open at least 8 to 12 cartons and spread the 125 pair sample across all SKUs.

Small orders need care too. AQL still applies to trial runs and low MOQs, but each defect carries more weight because the sample is small and the margin for error is tighter.

When should inspection happen during sock production?

Final inspection usually happens when goods are at least 80 percent packed. That is the standard shipment checkpoint. It is also late. If the wrong needle count or heel depth is found after packing, the fix may require unpacking, sorting, reboarding, and repacking.

For a new design, add an early production check after the first 50 to 100 pairs are knitted and toe closed. Check machine needle count, yarn count, pattern position, heel depth, toe closing, and stretch recovery. Common sock machines include 144 needle for thicker casual socks, 168 needle for many sports socks, and 200 needle for finer dress socks. Needle count affects logo clarity, hand feel, and cost.

Bulk lead time is often 20 to 35 days after sample approval for standard cotton blend socks. Dyed yarn programs, GOTS cotton, GRS recycled polyester, or custom packaging usually need more time. An inline inspection at about 20 percent production gives the factory time to correct knitting tension, boarding size, or packing errors before the final sock AQL inspection.

What measurements should a sock inspector record?

A useful sock AQL inspection report needs measured data, not only photos. For adult crew socks, record foot length, leg height, welt width, heel to toe length, pair weight, logo position, carton weight, and carton size. A common tolerance is plus or minus 0.5 cm on key dimensions. Pair weight often uses plus or minus 5 percent.

For fabric control, many sock programs use pair weight instead of GSM because socks are tubular knitted goods. A basic promotional ankle sock may weigh 25 to 35 g per pair. A midweight crew sports sock may weigh 45 to 70 g per pair. A thick terry winter sock can go above 90 g per pair. If weight is 12 percent below the approved sample, the yarn count or knitting density likely changed.

Inspectors should stretch the welt by hand or with a simple stretch board, hold it for 10 seconds, then check recovery after 30 seconds. They should compare color under D65 light when shade matters. For retail packs, scan several barcodes with a phone or scanner and match them to the purchase order, not only to the carton mark.

How should buyers write AQL terms into the purchase order?

Write the inspection rule in plain purchase order language. Example: Final random inspection by ANSI/ASQ Z1.4, normal inspection, General Inspection Level II, AQL Critical 0, Major 2.5, Minor 4.0. Shipment allowed only after passed inspection or written buyer release. Reinspection after failed inspection is paid by the factory when the failure comes from production or packing defects.

Add measurable product terms. State yarn composition, needle count, size tolerance, pair weight tolerance, packing ratio, carton quantity, carton gross weight limit, barcode placement, and required documents. Example: 168 needle crew sock, 75 percent cotton, 22 percent polyester, 3 percent spandex, 58 g per pair, plus or minus 5 percent, 1 pair per polybag, 120 pairs per master carton.

Certification claims must be fixed before yarn purchase. OEKO-TEX, GOTS, or GRS claims cannot be added after bulk knitting. The yarn records, labels, invoices, and transaction documents must match from the start. If the order also needs factory compliance records, buyers often ask for BSCI, Sedex, or ISO 9001 documents during order setup, not after inspection day.

Frequently Asked Questions

Is sock AQL inspection required for every order?

It is strongly recommended for a new supplier, new yarn, new logo, or first bulk order. For repeat orders with stable results, some buyers inspect every second or third shipment. Inspect every lot when size grading, stretch, toe closing, labels, or retail packaging changes.

What AQL level is common for custom socks?

A common setup is Critical 0, Major 2.5, Minor 4.0 under ANSI/ASQ Z1.4, General Inspection Level II. Premium retail programs may use Major 1.5. Low cost promotional socks often stay at Major 2.5 and accept more minor defects. Critical defects should stay at zero.

Can a failed AQL inspection still ship?

Yes, but only if the buyer gives written approval. In most cases, the factory sorts the lot, fixes the problem, and books reinspection. A barcode issue may be corrected in one day. Mixed defects such as holes, stains, size errors, and packing mistakes can take several days to sort.

How much does a sock inspection cost in China?

A third party inspection in China often costs about USD 150 to USD 300 per man day. One final sock inspection is usually finished in one day when cartons are packed, the packing list is ready, and the sample size is 200 pairs or less. Reinspection is normally charged again.

What should I send before sock AQL inspection?

Send the purchase order, approved sample photos, size spec, pair weight target, color standard, barcode files, carton marks, packing method, and defect classification sheet. If labels carry OEKO-TEX, GOTS, or GRS claims, send the related approval documents too. Keep one approved physical sample at the factory when possible.

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