AQL Calculator

Acceptance Quality Level

The AQL level is chosen based on the acceptable quality standard. Common levels include:

  • 0.65%: Very strict, often used for safety-critical components
  • 1.0%: Strict, used for high-quality consumer products
  • 2.5%: Standard level for most consumer products
  • 4.0%: More lenient, used for less critical items.


  • This calculator will determine the sample size and acceptance number based on the lot size and AQL level


Lot Size Determination


The lot size is the total number of items in a production batch. This is the starting point for AQL calculations.

AQL Level Selection


The AQL level is chosen based on the acceptable quality standard. Common levels are 1.0%, 2.5%, and 4.0%. A lower percentage indicates stricter quality control.

Sample Size Determination


Based on the lot size, a sample size is selected. In our simplified calculator:

  • For lots up to 150 items: Sample size is 20
  • For 151-280 items: Sample size is 32
  • For 281-500 items: Sample size is 50
  • For 501-1200 items: Sample size is 80
  • For over 1200 items: Sample size is 125.

Initial Acceptance Number


This is the maximum number of defective items allowed in the sample. In our calculator:

  • For sample size 20: Acceptance number is 1
  • For sample size 50: Acceptance number is 3
  • For sample size 80: Acceptance number is 5
  • For sample size 125: Acceptance number is 7

AQL Level Adjustment


The acceptance number is adjusted based on the chosen AQL level:

  • For 1.0% AQL (stricter): Reduce acceptance number by 1 (minimum 1)
  • For 2.5% AQL: No adjustment (this is our baseline)
  • For 4.0% AQL (more lenient): Increase acceptance number by 1.

Inspection Process


The determined sample size is randomly selected from the lot and inspected.

Decision Making


  • If the number of defects found is equal to or less than the acceptance number, the entire lot is accepted.
  • If the number of defects exceeds the acceptance number, the entire lot is rejected or subjected to 100% inspection.

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