AQL Sample Size Calculator
Determine sample sizes and acceptance criteria based on ISO 2859-1 standards.
What is an AQL Sample Size Calculator?
An AQL (Acceptable Quality Level) Sample Size Calculator is an essential tool used in quality control and manufacturing. Based on the ISO 2859-1 (or ANSI/ASQ Z1.4) standards, this calculator helps quality inspectors and procurement managers determine exactly how many units from a production lot need to be inspected to ensure the batch meets specific quality requirements. Instead of checking every single item, which is often time-consuming and expensive, AQL provides a statistically significant method to verify quality.
How to Use This AQL Tool
Using our calculator is straightforward. First, enter your total Lot Size, which is the total quantity of items in your shipment. Second, select your Inspection Level. General Level II is the industry standard for most consumer goods. Finally, choose your AQL Limit. Common limits are 0% for critical defects, 2.5% for major defects, and 4.0% for minor defects. The tool will then output the sample size and the maximum number of defects allowed before the entire lot is rejected.
Understanding Inspection Levels and AQL Table Logic
The calculator uses two main tables. The first table converts your lot size into a "Code Letter" (A through Q) based on the chosen inspection level. For example, for a lot size of 3,000 units at Level II, the code letter is 'K'. The second table maps this letter to a specific sample size. For 'K', the sample size is 125 units. The acceptance and rejection numbers are then determined by cross-referencing this code letter with your selected AQL percentage.
Frequently Asked Questions
What is the difference between General Level I, II, and III? Level II is the standard. Level I requires a smaller sample size (used when quality history is good), while Level III requires a larger sample size for higher risk products.
What happens if the defects exceed the limit? If the number of defects found equals or exceeds the 'Rejection' number, the entire lot is statistically likely to be below your quality standards and should be rejected or sorted.