How do you calculate AQL sample size?

Multiply lot size by your sampling rate, then take the larger of that figure and your minimum sample size. With a 1,200-part lot at 8% and an 80-part floor, the calculated sample is 96, which beats the floor, so 96 parts is the required sample.

What is a good AQL sampling rate?

There is no single number; it depends on AQL level and inspection severity. Common practical rates run 5-13% of small-to-medium lots, but for formal compliance you should map lot size to a code letter in ANSI/ASQ Z1.4 rather than picking a flat percentage.

Why include a minimum sample size?

Small lots can produce a calculated sample of only a handful of parts, which gives almost no statistical confidence. The minimum floor (80 in the example) guarantees you always inspect enough units even when the percentage math returns a tiny number.

AQL sample size vs full Z1.4 sampling plan?

This calculator returns how many parts to inspect. A full Z1.4 plan also tells you the maximum allowable defects (acceptance number) for a chosen AQL. Use this for quick sizing and the standard's tables for the formal accept/reject criteria.

Does a bigger lot always need a bigger sample?

Under a flat percentage it does, which is one weakness of this method. Real AQL tables flatten out so a 10,000-part lot needs only modestly more inspection than a 3,000-part lot, because sample size scales with the square-root of lot size, not linearly.

What happens if the calculated sample is below the minimum?

The formula returns the minimum instead. If 1,200 x 8% had produced only 60 parts, the 80-part floor would have governed and you'd inspect 80.

Quality & Metrology calculator

AQL Sample Size Calculator

AQL (Acceptable Quality Limit) sample size is the number of parts you pull from a production lot to decide whether the whole lot passes inspection. Quality engineers and incoming-inspection teams use it to apply ANSI/ASQ Z1.4-style sampling without inspecting 100% of a shipment. Getting the sample size right is what makes a statistical accept/reject decision defensible to customers and auditors. Pull too few and you miss defect rates; pull too many and you burn inspection labor on parts that are almost certainly fine.

What this calculator does

Estimate the AQL sample size for a lot from the lot size, a sampling rate tied to your inspection level, and a minimum sample.
Use it to plan AQL inspection workload before you look up the exact sample and acceptance number in ANSI/ASQ Z1.4.
It computes the required inspection sample size by taking the larger of (lot size x sampling rate) and your stated minimum sample size.

Formula used

Calculated sample = lot size × sampling rate
Required AQL sample size = max(calculated sample, minimum sample size)

Inputs explained

Inspection lot size: Number of parts in the lot being inspected.
Acceptable Quality Level (AQL): The AQL percent for the inspection (ANSI/ASQ Z1.4).
Minimum sample size: Floor on sample size regardless of lot size.

How to use the result

Use it when you receive or produce a discrete lot and need to set how many units to inspect before accepting or rejecting it.
This is a simplified percentage-of-lot model; it does not derive accept/reject numbers (Ac/Re) from an AQL level the way a full Z1.4 sampling plan table does.

Current U.S. benchmarks

U.S. manufacturing runs at 75.6% of capacity (Federal Reserve, May 2026). New factory orders are up 2.3% year over year (Census).

Common questions

How do you calculate AQL sample size? Multiply lot size by your sampling rate, then take the larger of that figure and your minimum sample size. With a 1,200-part lot at 8% and an 80-part floor, the calculated sample is 96, which beats the floor, so 96 parts is the required sample.
What is a good AQL sampling rate? There is no single number; it depends on AQL level and inspection severity. Common practical rates run 5-13% of small-to-medium lots, but for formal compliance you should map lot size to a code letter in ANSI/ASQ Z1.4 rather than picking a flat percentage.
Why include a minimum sample size? Small lots can produce a calculated sample of only a handful of parts, which gives almost no statistical confidence. The minimum floor (80 in the example) guarantees you always inspect enough units even when the percentage math returns a tiny number.
AQL sample size vs full Z1.4 sampling plan? This calculator returns how many parts to inspect. A full Z1.4 plan also tells you the maximum allowable defects (acceptance number) for a chosen AQL. Use this for quick sizing and the standard's tables for the formal accept/reject criteria.
Does a bigger lot always need a bigger sample? Under a flat percentage it does, which is one weakness of this method. Real AQL tables flatten out so a 10,000-part lot needs only modestly more inspection than a 3,000-part lot, because sample size scales with the square-root of lot size, not linearly.

Last reviewed 2026-05-12.