Interactive quality tool / acceptance sampling

AQL,
by the table.

MIL-STD-105E code letters and single sampling plans for normal, tightened and reduced inspection, with the operating-characteristic curve and the switching rules. Runs in your browser. Nothing you enter leaves your computer.

Important boundaryThis is a free calculator, not a controlled record. If a contract, drawing or customer specification names a different standard or plan, that requirement governs.
01 / define the lot and the plan

AQLs above 10 are listed only for nonconformities per 100 units (MIL-STD-105E §4.4.3). Your inputs are kept in this browser only, so you can come back to them.

Enter a lot size to see the code letter and the sampling plan.

The switching rules

Inspection starts on normal. MIL-STD-105E §4.7 moves you between normal, tightened and reduced inspection from the results of successive lots; §4.8 stops it. In the standard's words:

4.7.1 Normal to Tightened. When normal inspection is in effect, tightened inspection shall be instituted when 2 out of 2, 3, 4, or 5 consecutive lots or batches have been rejected on original inspection (i.e., ignoring resubmitted lots or batches for this procedure).
4.7.2 Tightened to Normal. When tightened inspection is in effect, normal inspection shall be instituted when 5 consecutive lots or batches have been considered acceptable on original inspection.
4.7.3 Normal to Reduced. When normal inspection is in effect, reduced inspection shall be instituted provided that all of the following conditions are satisfied:
a. The preceding 10 lots or batches (or more, as indicated by the note to Table VIII) have been on normal inspection and all have been accepted on original inspection; and
b. The total number of defectives (or defects) in the samples from the preceding 10 lots or batches (or such other number as was used for condition "a" above) is equal to or less than the applicable number given in Table VIII. If double or multiple sampling is in use, all samples inspected should be included, not "first" samples only; and
c. Production is at a steady rate; and
d. Reduced inspection is considered desirable.
4.7.4 Reduced to Normal. When reduced inspection is in effect, normal inspection shall be instituted if any of the following occur on original inspection:
a. A lot or batch is rejected; or
b. A lot or batch is considered acceptable under the procedures of 4.10.1.4, or
c. Production becomes irregular or delayed; or
d. Other conditions warrant that normal inspection shall be instituted.
4.8 Discontinuation of Inspection. If the cumulative number of lots not accepted in a sequence of consecutive lots on original tightened inspection reaches five, the acceptance procedures of this standard shall be discontinued. Inspection under the provisions of this standard shall not be resumed until corrective action has been taken. Tightened inspection shall then be used as if 4.7.1 had been invoked.

Try the switching rules

Enter a lot size and choose an AQL above to try the switching rules.

Source

Tables: MIL-STD-105E (10 May 1989), public domain. Engine version 1.0.0.

These plans and switching rules come from MIL-STD-105E (10 May 1989), a U.S. Department of Defense standard released for public use. ASQ describes ANSI/ASQ Z1.4 as an American national standard with direct lineage to MIL-STD-105E, and says the Department of Defense recommended it as the replacement when it stopped supporting MIL-STD-105E. ISO 2859-1 is the international acceptance sampling system for inspection by attributes indexed by AQL. This tool implements MIL-STD-105E; it is not Z1.4 or ISO 2859-1, and those standards may differ in details.

Single sampling only. Runs in your browser. Nothing you enter leaves your computer.

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