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Sampling Plan (AQL) Calculator

Work out sampling plan (aql) instantly with clear inputs, formula shown and shareable results.

About Sampling Plan (AQL) Calculator

Attribute sampling plans in the ANSI/ASQ Z1.4 tradition pick a sample size from the lot size and inspection level, then set an acceptance number from the AQL. This calculator reproduces that logic and adds the Poisson operating-characteristic point so you can see the producer's risk built into the plan.

Formulas

Acceptance number

Ac = round(Sample size x AQL %)

Operating characteristic

P(accept) = sum of Poisson(k; Sample x AQL) for k = 0..Ac

Worked example

With the default values below, Sampling Plan (AQL) Calculator returns Sample size of 315. Change any input above and every figure here is recalculated in your browser.

Inputs used

Lot size
5,000
Acceptable quality limitmaximum 100
1
Inspection levelone of Level I — reduced, Level II — normal, Level III — tightened
Level II — normal

Results

Sample size
315
Acceptance number (Ac)
3
Rejection number (Re)
4
Probability of accepting a lot at AQL
61.37%

Step by step

  1. 1Values used
  2. 2Acceptance number
  3. 3Operating characteristic
  4. 4Sample size= 315
  5. 5Acceptance number (Ac)= 3
  6. 6Rejection number (Re)= 4
  7. 7Probability of accepting a lot at AQL= 61.37

Assumptions and limits

  • The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
  • This is an estimate for general information and not professional financial, tax or legal advice. See the full disclaimer for the limits that apply to this kind of calculator.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Does a bigger lot need a much bigger sample?

No. Sample size grows far more slowly than lot size, because the discriminating power of a sample depends mainly on the sample itself.

Is AQL the quality level I should aim for?

No — it is the worst average quality that will still usually be accepted. Treat it as a contractual floor, not a target.

Related Calculators

Sampling Plan (AQL) Calculator – Calculate Sample size