How to use the AQL sample size and acceptance number calculator
How many pieces to pull and how many defectives to allow is set by a sampling table, not by judgment. The sequence has three steps: use the lot size and inspection level to find the sample size code letter, read the sample size for that letter, then read the accept number Ac and reject number Re under your AQL column.
Worked check: a lot of 2,000 pieces at general inspection level II with AQL 1.0% gives code letter K, a sample of 125 pieces, and Ac 3 with Re 4. Up to three defectives accept the lot and four reject it. Where the table shows an arrow instead of a number, the plan shifts one row to the first available sample size, and if that adjusted sample reaches the lot size you inspect 100% instead.
This tool follows ANSI/ASQ Z1.4 (identical in structure to ISO 2859-1) for single sampling under normal inspection, covering AQL 0.65% through 6.5%. It does not apply the switching rules for tightened and reduced inspection, and it does not cover double or multiple sampling plans, so check the published tables and your own inspection procedure before using the result in a supplier agreement.
Frequently asked questions
At general inspection level II a lot of 1,201 to 3,200 units gets code letter K, and single sampling normal inspection calls for 125 pieces. At AQL 1.0% the accept number is 3 and the reject number is 4, so up to three defectives pass the lot and four reject it.
No. The acceptable quality limit is the worst process average that the plan will still usually accept, not a defect target. A lot passing at AQL 1.0% is not a guarantee that the shipment contains 1% defects or fewer.