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ISO 2859-1 · International Inspection Standard

Stop guessing.
Start inspecting smarter.

AQL is the international standard that tells you exactly how many units to inspect from any batch — and how many defects are acceptable before you reject the whole lot. It removes guesswork, protects your brand, and is trusted by every major retailer on earth.

01
What is AQL?

AQL stands for Acceptable Quality Limit. A number — like 2.5 or 4.0 — that defines the maximum defective percentage acceptable in a shipment. AQL gives you a proven sample size and clear pass/fail rule, defined by ISO 2859-1.

02
Why does it matter?

Without AQL you over-inspect (wasting money) or under-inspect (letting defects reach customers). AQL creates a documented, defensible record — proof you followed international standards if a dispute arises with a supplier or buyer.

03
How it simplifies life

Instead of arguing about "how many to check," AQL gives a fixed answer based on lot size. Your QC team knows exactly what to inspect and how many defects trigger rejection. It removes subjectivity from quality decisions entirely.

How AQL Inspection Works — 5 Steps
1
Define lot size & AQL level
2
Get sample size & code letter
3
Randomly pull that many units
4
Count critical, major & minor defects
5
Compare to Ac/Re → Accept or Reject
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Critical Defects

Safety hazards or legal violations — sharp edges, missing warning labels, faulty wiring. Zero tolerance. One critical defect = entire lot rejected, no exceptions. AQL always set to 0.

⚠️
Major Defects

Defects likely to cause a complaint or return — wrong colour, broken zipper, missing component. Industry standard AQL is 2.5. Required by most global retailers as their minimum.

📌
Minor Defects

Slight spec deviations that won't affect function or cause returns — cosmetic scratches, off-centre labels. AQL typically set to 4.0. Higher count tolerated before rejection.

3
Defect Severity Levels
ISO
2859-1 Compliant
Lot Sizes Supported
0
Critical Defects Tolerated
AQL Sample Size Calculator
ISO 2859-1 · Single Sampling · Normal / Tightened / Reduced
Inspection Parameters
Total units in production run or shipment
AQL Levels by Defect Type
CriticalSafety / legal — zero tolerance
MajorCauses complaints / returns
MinorCosmetic / spec deviation
Inspection Requirements
Enter a lot size and click Calculate
Inspection Tracker
Log defects · Real-time verdict · Download report
Session Details
Defect Counts
Critical
Accept: 0 · Any = reject
0
PASS
Major
Enter sample size to auto-calculate
0
PASS
Minor
Enter sample size to auto-calculate
0
PASS
Total Defects0
Defect Rate
Critical (Found / Limit)0 / 0
Major (Found / Limit)0 / —
Minor (Found / Limit)0 / —
Awaiting Defect Log
AQL Reference Guide
ISO 2859-1 · ANSI/ASQ Z1.4 · Complete Reference
What is AQL?

AQL (Acceptable Quality Limit) is the maximum percentage of defective units acceptable during a random inspection of a production lot. Defined by ISO 2859-1 — used by every major retailer, importer, and manufacturer worldwide.

Simple version: You ordered 10,000 units. You can't check all of them. AQL tells you exactly how many to check (e.g. 200), and how many defects in those 200 triggers lot rejection. It's a statistically proven shortcut to a fair, consistent decision.

The AQL number (2.5, 4.0, etc.) does not mean "2.5% of products will be defective." It means the plan is designed to reject lots where the true defect rate exceeds that threshold with high statistical probability.

Inspection Levels

Controls the ratio of sample size to lot size. Higher level = larger sample = more confidence, but more cost and time.

LevelTypeWhen to Use
S-1 to S-4SpecialDestructive tests, expensive lab tests, very small samples needed
Level IGeneralTrusted supplier, want smaller samples to save cost
Level IIGeneralDefault for most industries — use this unless there's a reason not to
Level IIIGeneralNew suppliers, high-value goods, history of quality issues
Defect Types
TypeDefinitionExampleTypical AQL
CriticalSafety risk or legal violationExposed wiring, toxic material, missing safety label0 — Zero Tolerance
MajorLikely complaint or returnWrong colour, broken zipper, missing part2.5
MinorSlight deviation, won't affect functionMinor scratch, off-centre label4.0
Important: One critical defect in your sample = automatic lot rejection, regardless of major or minor counts.
Sample Code Letters

Your lot size + inspection level maps to a code letter (A–R), which sets the exact sample size.

Lot SizeLevel ILevel IILevel III
2 – 8A (n=2)A (n=2)B (n=3)
9 – 15A (n=2)B (n=3)C (n=5)
16 – 25B (n=3)C (n=5)D (n=8)
26 – 50C (n=5)D (n=8)E (n=13)
51 – 90C (n=5)E (n=13)F (n=20)
91 – 150D (n=8)F (n=20)G (n=32)
151 – 280E (n=13)G (n=32)H (n=50)
281 – 500F (n=20)H (n=50)J (n=80)
501 – 1200G (n=32)J (n=80)K (n=125)
1201 – 3200H (n=50)K (n=125)L (n=200)
3201 – 10000J (n=80)L (n=200)M (n=315)
10001 – 35000K (n=125)M (n=315)N (n=500)
35001 – 150000L (n=200)N (n=500)P (n=800)
150001 – 500000M (n=315)P (n=800)Q (n=1250)
500001+N (n=500)Q (n=1250)R (n=2000)
Switching Rules

ISO 2859-1 defines when to escalate or relax inspection based on supplier performance history.

SwitchConditionMeaning
Normal → Tightened2+ lots rejected out of 5 consecutiveSupplier struggling — increase scrutiny
Tightened → Normal5 consecutive lots acceptedSupplier recovered — resume standard
Normal → Reduced10 consecutive lots accepted + steady productionTrusted supplier — smaller samples OK
Reduced → NormalLot rejected or production irregularDon't stay reduced if quality slips
Industry Standard AQL Values
IndustryCriticalMajorMinor
Electronics / Tech00.652.5
Apparel / Textile02.54.0
Toys / Consumer Goods01.52.5
Automotive Parts00.651.5
Food / Pharma00.41.0
Furniture / Hardgoods02.54.0
Report
Done