AQL calculator
This calculator returns the ISO 2859-1 single sampling plan for normal inspection: the sample size code letter, the sample size, and the accept and reject numbers for critical, major and minor defects. It covers general levels I to III and special levels S-1 to S-4, follows the table's arrows, and has presets for furniture, rugs and apparel.
- Standard
- ISO 2859-1 / ANSI/ASQ Z1.4, normal inspection
- Levels
- S-1 to S-4, I, II, III
- AQLs
- Zero tolerance, 0.65 to 6.5
Your sampling plan
Code letter
J
Sample size
80
Lot 501 to 1,200 units, general ii
| Class | AQL | Sample | Accept | Reject |
|---|---|---|---|---|
| Critical | 0 (zero tolerance) | 80 | 0 | 1 |
| Major | 2.5 | 80 | 5 | 6 |
| Minor | 4.0 | 80 | 7 | 8 |
- Critical: zero tolerance, so accept 0 and reject 1 on the code letter's sample of 80.
Pass a class when defects found ≤ Accept; fail it at Reject or more. Each class is judged on its own.
How to read the result
- Code letter. From the lot size and inspection level (ISO 2859-1 Table I). It fixes the starting sample size.
- Sample size. How many units the inspector selects at random from the lot. If it equals or exceeds the lot, every unit is inspected.
- Accept and Reject. For each defect class: if the number of defects found is at or below Accept, that class passes; at or above Reject, it fails.
- Arrows. Where the standard's table has an arrow, the plan moves to the first row in the arrow's direction, and the sample size changes with it. The notes under the result say when this happens.
- Different sample sizes. If the classes end up with different sample sizes, each class is judged on its own plan. A practical way is to draw the largest sample and judge each class on the number of units its plan specifies.
For the full tables and a worked example, read AQL sampling explained. For percent defective versus defects per hundred units, see defect rate.
Presets by product
| Preset | Level | Critical / Major / Minor | Typical defects by class |
|---|---|---|---|
| Furniture | II | 0 / 2.5 / 4.0 | Critical: protruding nails, missing tip-over label or restraint on US dressers, unstable units. Major: sticking drawers, open joints, cracks, wrong finish. Minor: small marks on hidden surfaces. |
| Rugs | II | 0 / 2.5 / 4.0 | Critical: missing mandatory labels, live insects or mould. Major: size outside tolerance, colour not matching the approved sample, loose tufts or knots, wavy edges. Minor: small loose threads, light soiling that cleans off. |
| Apparel | II | 0 / 2.5 / 4.0 | Critical: broken needles or sharp objects, loose small parts on childrenswear. Major: open seams, wrong size label, measurements outside tolerance, shade variation. Minor: untrimmed threads, small stains that wash out. |
AQL calculator questions
Which inspection level should I use?
General level II unless you have a reason to change it. Use level I for low-risk goods from a proven supplier, level III for high-risk goods or after a failure, and special levels S-1 to S-4 for slow or destructive checks such as carton drop tests or measurements.
Why is the sample size the same for 501 and 1,200 units?
The code letter table groups lot sizes into ranges. Every lot from 501 to 1,200 units at general level II gets code letter J, which means 80 samples. Sample size grows much more slowly than lot size.
Why does my major or minor sample size differ from the code letter's?
Where the standard's table shows an arrow instead of accept and reject numbers, you use the first plan in the direction of the arrow, together with that plan's sample size. The calculator follows the arrow and tells you when it does.
What does AQL 0 mean here?
Zero tolerance: no defects of that class are accepted. The calculator uses the code letter's sample size with accept 0 and reject 1. It is a common setting for critical defects, though the standard itself has no AQL 0 column.
Does this calculator cover tightened or reduced inspection?
No. It gives single sampling plans for normal inspection, which is what most one-off pre-shipment inspections use. Switching rules for tightened and reduced inspection apply to a continuing series of lots.
Need the plan carried out at the factory?
Tell us the product, the factory's city and your ready date. We confirm the inspector, the notice time and the price before you book.