What Is AQL?
AQL (Acceptable Quality Level) is a statistical sampling standard used to determine whether a batch of products passes or fails inspection. It defines the maximum acceptable number of defects in a sample to consider the entire batch acceptable.
Key point: AQL doesn't mean "no defects" - it establishes an acceptable defect rate based on statistical sampling.
How AQL Works
- Define your order quantity (e.g., 5,000 units)
- Choose inspection level (typically Level II for general inspection)
- Look up sample size from AQL table
- Choose AQL values for critical, major, and minor defects
- Inspect the sample and count defects by category
- Accept or reject based on defect counts vs. limits
Example: For 5,000 units at Level II, you might inspect 200 samples. With AQL 2.5 for major defects, the batch passes if you find 10 or fewer major defects.
Common AQL Levels
| AQL Level | Defect Tolerance | Typical Use |
|---|---|---|
| 0 | Zero defects | Critical safety issues |
| 1.0 | ~1% | Critical functions |
| 2.5 | ~2.5% | Major defects (most common) |
| 4.0 | ~4% | Minor defects |
| 6.5 | ~6.5% | Cosmetic imperfections |
Industry standard: Most importers use 0 / 2.5 / 4.0 (Critical/Major/Minor).
Inspection Levels (I, II, III)
| Level | Sample Size | Cost | Confidence |
|---|---|---|---|
| Level I | Smaller | Lower | Reduced |
| Level II | Standard | Medium | Normal |
| Level III | Larger | Higher | Increased |
Level II is standard for most commercial inspections.
When to Use AQL
Use AQL when:
- Order quantity is 50+ units
- 100% inspection is impractical
- You need a standardized acceptance criteria
- Working with third-party inspectors
Don't rely solely on AQL when:
- Products have safety-critical components
- Order is very small (inspect 100%)
- First order from new supplier (consider tighter limits)