Enter your lot size, inspection level and AQL to get the exact sample size code letter, sample size, and Accept / Reject numbers — straight from the real ANSI/ASQ Z1.4 (ISO 2859-1) single sampling tables for normal inspection.
ANSI/ASQ Z1.4 — single sampling, normal inspection
Three inputs, one result — exactly how a professional QC inspector reads the standard.
The total number of finished units in the batch you want to inspect (not your sample — the whole production run).
Leave it on General II unless you have a reason to change it. Use a Special level only for destructive or expensive tests where a tiny sample is unavoidable.
This is the defect tolerance you have agreed with your supplier. A common split is AQL 2.5 for major defects and AQL 4.0 for minor defects (run the tool twice, once per defect class).
The calculator returns the code letter, the number of units to pull at random (n), and the Accept / Reject thresholds. Inspect n units: accept the lot at Ac defects or fewer, reject it at Re defects or more.
This calculator pairs with our hands-on QC playbooks for sourcing from China.
Inspection types, AQL sampling and how to build a QC process that protects every order.
GuideWhen to book, what inspectors check, costs, reports and handling a failed batch.
Service hubOn-the-ground inspectors in South China — book an AQL inspection on your next order.
AQL — the Acceptable Quality Limit — is the maximum percent defective considered acceptable as a process average for a sampling plan. Instead of inspecting 100% of a lot, you inspect a statistically determined sample and accept or reject the whole lot based on the defects found. A lower AQL means you tolerate fewer defects.
The single sampling plan for normal inspection from ANSI/ASQ Z1.4-2003 (R2018), numerically identical to ISO 2859-1 for these plans. The lot-size to code-letter table, the code-letter to sample-size table and the master Accept/Reject table are embedded directly from the published standard, including the arrow redirects.
General Inspection Level II is the default in most consumer-goods inspections and gives a balanced sample size. Level I uses a smaller sample (lower cost, less discrimination); Level III a larger sample (more discrimination, higher cost). Special levels S-1 to S-4 are for expensive or destructive tests where a very small sample is required.
After inspecting the sample, count the defects. If defective units are equal to or fewer than the Accept number, accept the lot. If equal to or greater than the Reject number, reject it. In a single sampling plan, Re is always Ac + 1.
A down arrow means use the first sampling plan below it (a larger sample size); an up arrow means use the first plan above it (a smaller sample size). This calculator follows the arrows automatically and shows the code letter and sample size it landed on. If that sample size meets or exceeds the lot, you inspect 100%.
No. AQL checks a representative random sample, not every unit, so it gives a statistically controlled risk of accepting a bad lot rather than a guarantee of zero defects. For critical or safety defects, many buyers set AQL 0 (zero tolerance) for that class, or add 100% screening.
We run AQL inspections on the factory floor in Shenzhen, Guangzhou and across South China — and tell you straight whether your order is shippable. Book a free 15-minute consult.
Book a Free 15-Min Consult →Free email: our pre-shipment inspection checklist and AQL cheat-sheet. No spam.