AQL Sampling Table

Finds the code letter, sample size, acceptance number (Ac) and rejection number (Re) in the single sampling tables of ISO 2859-1 and ANSI/ASQ Z1.4 from the lot size, inspection level and AQL. Use it in incoming or outgoing inspection.

How to use

1. Enter the "Lot size": the number of items submitted for inspection at one time.
2. Choose the "Inspection level" (II by default), the "AQL", the "Inspection severity" and the "Standard".
3. Read the "Code letter", "Sample size", "Acceptance number" and "Rejection number". With Ac or fewer defectives the lot is accepted; with Re or more it is rejected.
4. The "Compare AQLs", "OC curve", "Full tables" and "Switching rules" tabs give details.

How it works

• When the table cell is an arrow, the first plan in its direction is used and the page says so. If the sample size reaches the lot size, the page calls for 100 % inspection.
• The OC curve is binomial, hypergeometric when the lot is at most 10 times the sample, and Poisson for nonconformities per 100 items.
• For reference only. For contracts and inspections, check the text of the standard itself.

Questions and answers

How many items do I inspect for a lot of 5,000 at AQL 2.5?

At level II, normal inspection: code letter L, sample size 200, Ac 10, Re 11. With 10 or fewer defectives the lot is accepted.

What is AQL?

The acceptance quality limit: the worst process average that is tolerable over a series of lots, in percent nonconforming or nonconformities per 100 items. The "OC curve" tab shows the chance of accepting a lot at the AQL.

What is the difference between inspection levels I, II and III?

For the same lot, a higher level gives the same or a larger sample. II is used unless another is specified; S-1 to S-4 are for cases where only small samples can be taken.

Are ISO 2859-1 and ANSI Z1.4 the same tables?

Normal inspection is the same. Tightened differs at code letter A, AQL 10, and in reduced inspection Z1.4 keeps a gap between Ac and Re.