Tool
Enter lot and AQL values
Planning logic: Lot size -> code letter -> sample size -> accept or reject number
Calculator Library / Inspection
AQL Sampling Calculator
Estimate acceptance and rejection numbers from lot size and AQL so incoming quality and receiving teams can plan sampling decisions more consistently.
Breakdown
Plan logic
| Element | Value | Meaning |
|---|
Instructions
How to use this app
- Enter the lot size to be inspected.
- Select the inspection level and AQL target.
- Optionally enter the expected incoming defect rate for a probability comparison.
- Click Calculate Plan to estimate code letter, sample size, and accept or reject numbers.
- Use the result for planning and align the final released plan to the formal sampling standard required by your organization or customer.
What This AQL Calculator Helps You Decide
This calculator helps receiving, supplier quality, and incoming inspection teams estimate how many units to inspect and where the acceptance and rejection threshold should sit for a given lot size and AQL target.
It is intended as a practical planning tool. Final released plans should still be checked against the exact sampling standard and company policy in force.
Core Logic
| Step | Meaning |
|---|---|
| Lot size to code letter | Maps the lot into a standard sample-size band. |
| Code letter to sample size | Converts the band into an inspection quantity. |
| AQL to accept or reject threshold | Defines how many defects are allowed before the lot is rejected. |
Worked Example
A lot of 2,500 pieces at General II with an AQL of 1.00% maps to code letter K in this planning model. That produces a sample size of 125 pieces with a small acceptance number and a reject number one defect higher.
How to Interpret the Results
- Larger lot sizes: generally drive the code letter and sample size upward.
- Tighter AQL: lowers the number of defects tolerated before rejection.
- Expected defect rate above AQL: reduces the chance the lot will pass.
- Planning estimate only: use the result to prepare, then confirm against the official standard you follow.
AQL Sampling Frequently Asked Questions
What does AQL mean?
AQL means Acceptable Quality Level, the defect level used to design a sampling plan.
Does AQL guarantee that every accepted lot is good?
No. It is a probabilistic sampling approach, not a guarantee that every non-sampled unit is conforming.
Why does the calculator show accept and reject numbers?
Those numbers define the decision rule for the inspected sample. At or below the accept number the lot passes, and at or above the reject number it fails.
Can I use this instead of my company's official standard?
No. Use it for planning and education, then verify the final plan against the standard and customer requirements your organization uses.
When should AQL plans be tightened?
Tighten them when supplier performance degrades, escapes increase, or the item has higher quality, safety, or customer risk.
Related Templates and Guides
Download the Six Sigma Calculator Suite
Use the workbook when inspection planning needs to connect to defect and capability analysis.
Read the Quality Standards Guide
Use the guide when inspection plans need to align with broader quality-system and customer requirements.