Lot Quality Assurance Sampling Calculator

Work out lot quality assurance sampling instantly with clear inputs, formula shown and shareable results.

About Lot Quality Assurance Sampling Calculator

Applies the lot quality assurance sampling rule: a lot is rejected when the number of shortfalls in a small sample exceeds the decision value.

Formula

LQAS decision rule

Accept the lot if observed shortfalls are at or below the decision value; reject otherwise. Sample sizes of 19 with a decision value derived from the coverage target are standard

Worked example

With the default values below, Lot Quality Assurance Sampling Calculator returns LQAS decision of Lot accepted — coverage likely at or above the target. Change any input above and every figure here is recalculated in your browser.

Inputs used

Sample size per lotaccepts 5–100: 19
Decision valueaccepts 0–50: 3
Shortfalls observedaccepts 0–100: 2
Coverage targetaccepts 10–100: 80

Results

LQAS decision: Lot accepted — coverage likely at or above the target
Observed coverage in the sample: 89.47%
Shortfalls allowed: 3
Further shortfalls before rejection: 1

Step by step

1Values used
2LQAS decision rule
3LQAS decision= Lot accepted — coverage likely at or above the target
4Observed coverage in the sample= 89.47
5Shortfalls allowed= 3
6Further shortfalls before rejection= 1

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Why is a sample of 19 used?

It is the smallest sample that classifies coverage against common thresholds with acceptable error rates, which makes supervision affordable.

Does LQAS estimate coverage?

Not precisely for a single lot; it classifies lots, and aggregating lots gives a coverage estimate.