Define the lot correctly
Use the quantity produced under reasonably consistent conditions. Mixed products, colors, sizes, or production periods may require stratification or separate lots.
Quick Answer
What does this calculator do?
An AQL sample size calculator helps prepare an inspection plan for a production lot. Enter lot size, general inspection level, AQL, a defect rate to test, and inspection cost per unit. The tool returns a code-letter and sample-size planning reference, sample coverage, and the mathematical probability of finding at least one defect at the tested rate.
Planning outputsCode letter, sample size, coverage, probability
Inspection levelsGeneral I, II, and III
Current referenceISO 2859-1:2026 context
Important limitNo official Ac/Re decision numbers
Interactive Workspace
Method reviewed 2026-07-16Build a transparent planning scenario
Your inputs are saved only in this browser for convenience. Every output is directional and should be replaced with current project evidence.
Methodology
How to use the aql sample size calculator
The calculator is deliberately transparent: it organizes buyer inputs, shows the resulting logic, and identifies where professional confirmation is still required.
Choose inspection level
General Level II is a common planning starting point; Level I samples less and Level III samples more. The contractual plan should state the chosen level.
Set defect categories
Critical, major, and minor defects should have written definitions and may use different AQL values. Do not treat all defects as equally severe.
Confirm the formal plan
Use the current standard, inspection provider, and purchase agreement to confirm sample size, acceptance and rejection numbers, switching rules, and special levels.
Interpretation
How to read the result
Use the output to compare scenarios and prepare better questions, not to turn uncertain assumptions into false precision.
AQL is not an allowed defect promise
AQL indexes an acceptance-sampling plan. It does not mean every shipment may contain that exact percentage of defects or that the buyer accepts known defective products.
Sample coverage falls as lots grow
Larger lots do not require inspecting the same percentage of units. Statistical sampling focuses on decision risk rather than a fixed percentage of the lot.
Detection probability adds context
The calculator shows the chance of seeing at least one defect if units are sampled independently at the entered true defect rate. This is not the same as an official Ac/Re rule.
Evidence Checklist
Improve the inputs before making a decision
Stronger inputs make the tool more useful. Replace placeholders with dated documents, comparable quotations, test results, and provider confirmations.
Write an inspection checklist
Specify product, workmanship, dimensions, function, labeling, packaging, quantity, barcode, and regulatory checks with objective tolerances and approved references.
Stratify the sample
Spread selected cartons and units across production lines, time periods, colors, sizes, and carton locations where relevant. A convenient sample is not a random sample.
Plan corrective action
State what happens after a failed inspection: rework, sorting, reinspection, root-cause evidence, concession, or rejection. Sampling only helps when the decision path is clear.
Sources and Boundaries
Method references and related guidance
These references explain the framework behind the inputs. Destination rules and current project evidence remain authoritative for the actual order.
Open to Transparent Buyer Feedback
LIFA Global Trade welcomes honest customer reviews on Trustpilot. Real feedback helps buyers evaluate our China sourcing support, communication, and coordination services with transparency.
Your honest feedback helps us improve our sourcing support and helps other buyers make informed decisions.
Frequently Asked Questions
AQL Sample Size Calculator questions
Concise answers to the questions buyers should settle before relying on a planning result.
AQL means acceptance quality limit. It is an index used in acceptance-sampling schemes for lot-by-lot inspection, together with lot size, inspection level, sample size, and acceptance rules.
No. It is a common starting point, but the appropriate level depends on contract, risk, inspection history, product complexity, and the applicable sampling plan.
No. It provides a transparent planning reference and detection probability. Confirm official Ac/Re numbers and switching rules using the current standard and inspection provider.
Critical defects can create unsafe or unlawful conditions; major defects materially affect use or sale; minor defects depart from specification without the same impact. Definitions must be product-specific.
A fixed percentage is easy to explain but does not preserve the same statistical decision properties across lot sizes. Use a documented sampling plan when acceptance sampling is required.
Special levels can be appropriate for destructive, expensive, or time-consuming tests. They should be chosen deliberately because smaller samples provide less information.
Related Calculators
Continue the sourcing decision
Cost, supplier, quality, inspection, and timeline decisions influence one another. Use the related workspace that addresses the next uncertainty.
💰
Landed Cost
Open the dedicated landed cost workspace with its own inputs, method, result explanation, and verification guidance.
Open Tool🛃Duty & Tariff
Open the dedicated duty & tariff workspace with its own inputs, method, result explanation, and verification guidance.
Open Tool⚖️Supplier Comparison
Open the dedicated supplier comparison workspace with its own inputs, method, result explanation, and verification guidance.
Open Tool🗂️Break-Even
Open the dedicated break-even workspace with its own inputs, method, result explanation, and verification guidance.
Open Tool🔍Quality Cost
Open the dedicated quality cost workspace with its own inputs, method, result explanation, and verification guidance.
Open Tool📅Timeline
Open the dedicated timeline workspace with its own inputs, method, result explanation, and verification guidance.
Open Tool
Need China-side evidence?
Ask LIFA to review the assumptions behind the result.
Send the product specification, supplier quote, destination, and the questions the calculator revealed.
