AQL Chart

How AQL appears in an inspection report

Sources checked

Parts of this article describe common industry practice, not official rules; statements taken from official pages are listed under Sources.

An AQL line in an inspection report is usually one part of a sampling plan that the inspector applied to a lot. The report normally shows the lot size, the inspection level, the AQL, the sample size, and the acceptance and rejection numbers for each defect class. Reading these entries against the sampling table shows whether the reported result follows from the counts.

What a report usually lists

A third-party inspection company's report, or an in-house report, commonly carries these entries for sampling:

  • The lot or order quantity.
  • The inspection level.
  • The AQL used for each defect class, such as critical, major and minor.
  • The sample size inspected.
  • The acceptance number (Ac) and the rejection number (Re) for each class.
  • The number of defects or defective units found in each class.
  • The result for each class, and the overall result.
  • A reference to the sampling standard and the edition that the order names.

A report can show different sample sizes for different defect classes. In that case, each class has its own row of sampling entries, and the reader should not assume one sample size covers the whole report.

What a buyer usually checks when the report arrives

Buyers often start with the header, then move to the class tables. A common approach is to check these points in order:

  • The lot size, inspection level and AQL match the order.
  • The sample size, Ac and Re for each class match the sampling table for that lot size, level and AQL.
  • The defect counts are listed separately for each class.
  • The photos and the defect list support the counts in the table.
  • The result for each class follows from its count, and the overall result follows from the class results.

If a check fails, the next step is usually what the order says. The order may describe re-inspection, rework, sorting or another step, and the buyer and supplier can agree on it in writing.

Where readers usually slip

Several misreadings come up often:

  • Reading the AQL as a percentage of defective units the lot is allowed to contain. The AQL is used to select a plan from the table, and the acceptance and rejection numbers come from that plan.
  • Using the production quantity from a supplier's document as the lot size, when the order quantity or the lot as presented for inspection is the figure the table needs.
  • Taking the sample size from a neighbouring row after moving between lot ranges or AQL columns.
  • Reading a class result as the overall result, or the overall result as covering every class.
  • Comparing a defect count with the wrong column, so that a count that should be checked against Ac is compared with Re, or the other way round.

A report that lists the counts, the plan entries and the result for each class makes these points easier to verify.

What the table shows

The values below are the site's transcription of Table I and Table II-A of MIL-STD-105E, for single sampling under normal inspection. They are table values, not quotations from the standard.

  • Lot size 3,201 to 10,000 units, general inspection level II, code letter L (sample size 200 for that letter):
  • AQL 2.5: sample size 200, accept 10, reject 11.
  • AQL 4.0: sample size 200, accept 14, reject 15.
  • Lot size 91 to 150 units, general inspection level II, code letter F (sample size 20 for that letter):
  • AQL 1.0: the plan uses the sample size of letter E, which is 13. Accept 0, reject 1.
  • AQL 1.5: the plan uses the sample size of letter G, which is 32. Accept 1, reject 2.

A worked example from the table

Take a lot of 5,000 units, which falls in the range 3,201 to 10,000. At general inspection level II, the code letter is L. The AQL values used here are examples for reading the table, not a statement of which AQL is usual for any class or product.

At AQL 2.5, the plan is sample size 200, accept 10, reject 11. Using the site's count-and-compare rule, if the number of defective units in that class is Ac or fewer, the lot is accepted; if it is Re or more, the lot is rejected. In this example, 10 or fewer defective units at AQL 2.5 accepts on that class, and 11 or more rejects.

At AQL 4.0, the plan is sample size 200, accept 14, reject 15. The same reading applies: 14 or fewer defective units accepts on that class, and 15 or more rejects.

Now take a lot of 100 units, which falls in the range 91 to 150. At general inspection level II, the code letter is F. At AQL 1.0, the plan uses the sample size of letter E: sample size 13, accept 0, reject 1. At AQL 1.5, the plan uses the sample size of letter G: sample size 32, accept 1, reject 2. A report that lists different AQLs for different classes can therefore show different sample sizes, as these rows do.

The table footnote adds one point to check. If the sample size equals or exceeds the lot or batch size, the footnote calls for 100 percent inspection.

Where the table values come from

These tables come from MIL-STD-105E, Sampling Procedures and Tables for Inspection by Attributes (U.S. Department of Defense, 10 May 1989). ANSI/ASQ Z1.4 and ISO 2859-1 descend from it. The tables here were not compared cell by cell with the current paid editions of ANSI/ASQ Z1.4 or ISO 2859-1. Where a contract or purchase order names a standard and an edition, that one governs.

Sources

  • MIL-STD-105E, Sampling Procedures and Tables for Inspection by Attributes, U.S. Department of Defense, 10 May 1989: Table I and Table II-A with its legend and footnote. Page scans: archive.org/details/MIL-STD-105E_1. Read 11 October 2026.

Checked 11 October 2026.

This page is an unofficial reference, not affiliated with ISO, ASQ or ANSI, and where your contract names ANSI/ASQ Z1.4, ISO 2859-1 or another standard, use the tables of that edition.

AQL Chart Guide