AQL (Acceptable Quality Level) vs. PPM (Parts per Million) - Equivalences?

Marc

Hunkered Down for the Duration
Staff member
AQL vs PPM

From: David Chan, Jenny Chan

> ...can anyone tell me that the relationship between AQL and PPM..
> somebody told me that 0.065% AQL = 650PPM, is it true ???
>
> i personally think that it isn't , but cannot get proven evident.. can
> u help me ??
>
> tx..
>
> Jenny Chan...

Marc

Hunkered Down for the Duration
Staff member
I can't help you with the actual numbers off hand, but AQL is Acceptable Quality Level as a per cent. Used in inspection to determine sample size, you decide the AQL level you want and a chart gives you a sample size. Your knowns are the lot size which you look up on the table, and the AQL level you want.

PPM is Parts Per Million which can be converted to a %.

Maybe one of the others can help you out with details and numbers.

D

Don Winton

Acceptable Quality Level (AQL) is defined by ANSI/ISO/ASQC A3534 as follows: "When a continuing series of lots is considered, a quality level which for purposes of sampling inspection is the limit of satisfactory process average."

The associated AQL and Lot Tolerance Percent Defective (LTPD) are summarized graphically by the operating characteristic curve.

…somebody told me that 0.065% AQL = 650PPM, is it true ???

Strictly speaking, no. But, a case could be made that if the AQL was, in fact, 0.065%, then the PPM might be 650. The problem is, AQL is an Acceptable Quality level, not the Actual Quality Level. AQL is the quality level that would be detectable under a certain sampling plan.

Also strictly speaking, the LTPD * 10,000 = PPM nonconforming.

Regards,
Don

Marc

Hunkered Down for the Duration
Staff member
I got this e-mail today. I know this is an old thread, but it's worth opening back up for a bit.

On 6/18/02 6:29 PM, arnulfom wrote:

> Hi Marc,
>
> Sorry for bother you, look, I saw a thread at the cove forum where you talk
> about the PPM vs AQL.
>
> I have a doubt and could not get in touch with any one in the forum due to
> failure comunication problems, my question as follows:
>
> If I have an AQL=0.1, which is the number of defective parts per million I
> will give my customer?<hr>Also see AQL (Acceptable Quality Level) vs. LTPD (Lot Tolerance Percent Defective)

and

Information about PPM since giving up AQL - Historical description of requirements

Proud Liberal

Quite Involved in Discussions
You can't get to PPM from AQL. There are many OC curves that will pass through a single AQL. If you're interested in the conversion, you'll need to specify both ends of the curve and then look at the associated AOQL levels. Typically, you'll find the worst case AOQL level at Pa = .50.

Geoff Cotton

Quite Involved in Discussions
I hate the word "Acceptable" in AQL, it suggests we are doomed to failure before we start.

Example Work Instruction/Procedure for AQL (Acceptable Quality Level) AQL - Acceptable Quality Level 4
S What are typical Acceptable Quality Levels (AQL) adopted in Food industry? Food Safety - ISO 22000, HACCP (21 CFR 120) 1
W Application of AQL (Acceptable Quality Level) Concept AQL - Acceptable Quality Level 15
M AQL (Acceptable Quality Level) for Mixed Part Defect IATF 16949 - Automotive Quality Systems Standard 1
AQL (Acceptable Quality Level) Report Form example wanted AQL - Acceptable Quality Level 1
AQL - How do I determine Acceptable Quality Level (AQL) for In-Process Inspection? AQL - Acceptable Quality Level 2
A What is the purpose of using AQL (Acceptable Quality Level) for Sampling? AQL - Acceptable Quality Level 3
K So confused with AQL - How does AQL (Acceptable Quality Level) fit with my company AQL - Acceptable Quality Level 7
Y Advice on this real case on AQL (Acceptable Quality Level)? AQL - Acceptable Quality Level 3
L AQL (Acceptable Quality Level) Question Quality Manager and Management Related Issues 7
H Need help with AQL (Acceptable Quality Level) for a QC inspection AQL - Acceptable Quality Level 8
S AQL (Acceptable Quality Level) for Safety Critical Parts AQL - Acceptable Quality Level 13
AQL (Acceptable Quality Level) Sampling Plan for Small Lots AQL - Acceptable Quality Level 8
M AQL (Acceptable Quality Level) for Zero Defects AQL - Acceptable Quality Level 13
H AQL (Acceptable Quality Level) for Medical Devices AQL - Acceptable Quality Level 14
Q AQL - How do I find Acceptable Quality Level? AQL - Acceptable Quality Level 75
D Problem with AQL (Acceptable Quality Level) AQL - Acceptable Quality Level 9
C ISO 9001:2000 In Textile Industries - AQL (Acceptable Quality Level) ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 2
AQL - Acceptable (Assured) Quality Level AQL - Acceptable Quality Level 0
C Linking Acceptable Quality Levels (AQL) and Average Output Quality AQL - Acceptable Quality Level 7
Custom hardware product - What acceptable quality level (AQL) is expected in the US? AQL - Acceptable Quality Level 4
LTPD (Lot Tolerance Percent Defective) vs. AQL (Acceptable Quality Level) Definitions AQL - Acceptable Quality Level 5
N Setting AQL (Acceptable Quality Level) on C=Zero inspections AQL - Acceptable Quality Level 16
K AQL (Acceptable Quality Level) vs. IRR (Initial Reliability Requirement) AQL - Acceptable Quality Level 6
W Acceptable Quality Levels (AQL) - What is the usage of AQL 100 to 1000? AQL - Acceptable Quality Level 10
L AQL (Acceptable Quality Level) vs. LTPD (Lot Tolerance Percent Defective) AQL - Acceptable Quality Level 12
M Applying AQL when 0 defects are acceptable AQL - Acceptable Quality Level 9
AQL, Consumer Risk and MA Statistical Analysis Tools, Techniques and SPC 2
AQL - How to count samples with defects for each defect class AQL - Acceptable Quality Level 17
Defining sampling plan for different AQL AQL - Acceptable Quality Level 1
ARMY AQL - Requirements which don't have an AQL associated with them Manufacturing and Related Processes 2
AQL table - I need to sample 1250pcs AQL - Acceptable Quality Level 3
Sampling plan for a customer who wants AQL 1.0 (per ANSI Z1.4) AQL - Acceptable Quality Level 5
How to interpret AQL sampling tables AQL - Acceptable Quality Level 5
AQL sampling bags of parts Inspection, Prints (Drawings), Testing, Sampling and Related Topics 5
Sampling processes - Who must define the AQL level? AQL - Acceptable Quality Level 9
AQL for Effectiveness Check - What AQL tiers to use on this type of sampling? Nonconformance and Corrective Action 9
AQL Inspector's Rule - bring into CQE Exam? Professional Certifications and Degrees 5
The question asks about sampling plans and AQL Reliability Analysis - Predictions, Testing and Standards 5
Defining Acceptance Quality Level, I need clarity on AQL 1.5, 2.5, 4.0 AQL - Acceptable Quality Level 5
Receiving Inspection AQL - Am I allowed to just pick a AQL? Inspection, Prints (Drawings), Testing, Sampling and Related Topics 10
Established a c=0 "AQL" or "RQL" table AQL - Acceptable Quality Level 5
AQL Sampling Plan SOP / WI - Medical Device Industry Inspection, Prints (Drawings), Testing, Sampling and Related Topics 14
L How to calculate the Probability of Deficiency of the AQL of an Inspection AQL - Acceptable Quality Level 16
Setting Acceptance Quality Limits (AQL) for New Medical Devices ISO 13485:2016 - Medical Device Quality Management Systems 4
K AQL for Sterile Product - Laminate Tubes 21 CFR Part 820 - US FDA Quality System Regulations (QSR) 5
M How to Mathemetically Derive the AQL Tables given Lot Sizes AQL - Acceptable Quality Level 5
L AQL ANSI z1.4 & z1.9 - What are the differences between these 2 standards? AQL - Acceptable Quality Level 5
P RQL/AQL from Attribute Data Six Sigma 1
B Designing a Sampling Plan - AQL AQL - Acceptable Quality Level 19