Free Tool
AQL Sampling Calculator
Based on ISO 2859-1 / ANSI/ASQ Z1.4 — the global standard for acceptance sampling. Enter your shipment lot size to instantly calculate the required sample size and acceptance criteria.
Inspection Parameters
Total number of units in the production batch or shipment
General Level II is standard for most consumer goods inspections
Critical: 0 | Major: 2.5 | Minor: 4.0
Fill these in after your inspection to get an instant Pass/Fail verdict
Enter your lot size and press Calculate Sample Size to see your ISO 2859-1 sampling plan.
Understanding AQL
What is AQL?
AQL is the maximum percentage of defective units that is considered acceptable during routine inspection. It does not mean you accept defects — it defines a statistical threshold at which a batch is accepted or rejected. AQL is defined in ISO 2859-1 (international) and ANSI/ASQ Z1.4 (US). A shipment is sampled, not 100% inspected, because 100% inspection is impractical for large production runs and can itself introduce errors.
Reference
AQL Reference Tables
The complete ISO 2859-1 lookup — code letters by lot size and the single-sampling acceptance numbers. Download as a PDF for the floor.
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AQL Sampling Tables — ISO 2859-1 Normal Inspection
Table A — Sample Size Code Letters
| Lot Size Range | S-1 | S-2 | S-3 | S-4 | I | II | III |
|---|---|---|---|---|---|---|---|
| 2 – 8 | A | A | A | A | A | A | B |
| 9 – 15 | A | A | A | A | A | B | C |
| 16 – 25 | A | A | B | B | B | C | D |
| 26 – 50 | A | B | B | C | C | D | E |
| 51 – 90 | B | B | C | C | C | E | F |
| 91 – 150 | B | B | C | D | D | F | G |
| 151 – 280 | B | C | D | E | E | G | H |
| 281 – 500 | B | C | D | E | F | H | J |
| 501 – 1,200 | C | C | E | F | G | J | K |
| 1,201 – 3,200 | C | D | E | G | H | K | L |
| 3,201 – 10,000 | C | D | F | G | J | L | M |
| 10,001 – 35,000 | C | D | F | H | K | M | N |
| 35,001 – 150,000 | D | E | G | J | L | N | P |
| 150,001 – 500,000 | D | E | G | J | M | P | Q |
| 500,001+ | D | E | H | K | N | Q | R |
Table B — Single Sampling Plans (Ac / Re by AQL)
Each cell shows Accept / Reject numbers. ↑ = use next larger plan, ↓ = use next smaller plan.
| Code | Sample Size | AQL 0.65 | AQL 1.0 | AQL 1.5 | AQL 2.5 | AQL 4.0 | AQL 6.5 |
|---|---|---|---|---|---|---|---|
| A | 2 | ↑ | ↑ | ↑ | ↑ | ↑ | ↑ |
| B | 3 | ↑ | ↑ | ↑ | ↑ | ↑ | 0 / 1 |
| C | 5 | ↑ | ↑ | ↑ | ↑ | 0 / 1 | 0 / 1 |
| D | 8 | ↑ | ↑ | 0 / 1 | 0 / 1 | 1 / 2 | 1 / 2 |
| E | 13 | ↑ | 0 / 1 | 0 / 1 | 1 / 2 | 1 / 2 | 2 / 3 |
| F | 20 | 0 / 1 | 0 / 1 | 1 / 2 | 1 / 2 | 2 / 3 | 3 / 4 |
| G | 32 | 0 / 1 | 1 / 2 | 1 / 2 | 2 / 3 | 3 / 4 | 5 / 6 |
| H | 50 | 1 / 2 | 1 / 2 | 2 / 3 | 3 / 4 | 5 / 6 | 7 / 8 |
| J | 80 | 1 / 2 | 2 / 3 | 3 / 4 | 5 / 6 | 7 / 8 | 10 / 11 |
| K | 125 | 2 / 3 | 3 / 4 | 5 / 6 | 7 / 8 | 10 / 11 | 14 / 15 |
| L | 200 | 3 / 4 | 5 / 6 | 7 / 8 | 10 / 11 | 14 / 15 | 21 / 22 |
| M | 315 | 5 / 6 | 7 / 8 | 10 / 11 | 14 / 15 | 21 / 22 | ↓ |
| N | 500 | 7 / 8 | 10 / 11 | 14 / 15 | 21 / 22 | ↓ | ↓ |
| P | 800 | 10 / 11 | 14 / 15 | 21 / 22 | ↓ | ↓ | ↓ |
| Q | 1250 | 14 / 15 | 21 / 22 | ↓ | ↓ | – | – |
| R | 2000 | 21 / 22 | ↓ | – | – | – | – |
© AIU Inspections | aiuinspections.com | Reference: ISO 2859-1 / ANSI/ASQ Z1.4
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