AQL sample size calculator for garment inspection

It looks the answer up in two tables from ISO 2859-1; it does not calculate anything. The first table turns your lot size and inspection level into a sample size code letter: 5,000 pieces at General Level II is letter L. The second table, the single sampling plans for normal inspection, gives each letter a sample size and, under each AQL, an accept and a reject number: letter L means 200 pieces, with 10 accepted and 11 rejected at AQL 2.5, and 14 and 15 at AQL 4.0. The sample depends on the lot size band, not the exact quantity, so 3,201 pieces and 10,000 pieces both get a sample of 200. We typed the tables in from the printed standard, and every time the site is built a check compares them with the figures in our AQL guide and stops the build if one differs. Always confirm against the table your inspector or your retailer’s manual uses.

Because some cells in the printed table hold an arrow instead of numbers, where the table has no plan for that combination of code letter and AQL. The instruction printed with the table is to use the first sampling plan the arrow points to, with that plan’s sample size as well as its accept and reject numbers. A lot of 100 pieces at General Level II is letter F, a sample of 20. At AQL 2.5 the table gives numbers for F: accept 1, reject 2. At AQL 1.5 it has a down arrow, so the plan becomes letter G: 32 pieces, accept 1, reject 2. On a small lot, major and minor defects can therefore end up with different sample sizes, and the calculator shows each one and says which arrow it followed. If a plan’s sample is as large as the lot, the instruction is to inspect every piece.

Enter the pieces of one style that will be offered for inspection together. The standard applies to lots from one producer using one process, so the same style made in two factories is two lots, each with its own sample. Different garments, such as a hoodie and a t-shirt on one purchase order, are normally inspected as separate lots too. The colours and sizes of one style are usually one lot, with the sample drawn at random across colours, sizes and cartons. How you split matters: one lot of 5,000 pieces needs a sample of 200 at General Level II, while two lots of 2,500 need 125 each, 250 in total. If a style ships in two parts, each part offered for inspection is usually treated as its own lot. Write the lot definition, the inspection level and the AQLs into the purchase order before production, so the factory, the inspector and you count the same thing.