Quality & Metrology worked example

Sampling Plan Size at 7.2% sampling rate: a worked example

Here is what the math looks like when conditions slip. We hold every other input steady and drop sampling rate to 7.2%, then walk the calculation through step by step. Estimate sample size for a lot from the lot size, a percentage sampling rate, and a minimum sample required by your plan.

The inputs for this scenario

  • Lot size: 2,000 parts (held at the documented default)
  • Sampling rate: 7.2 % (the input this scenario stresses; the baseline uses 10)
  • Minimum sample size: 50 parts (held at the documented default)

Working through the calculation

  • The calculation starts from the formula this tool documents: Calculated sample = lot size × sampling rate.
  • Required sample size works out to 145 samples at these inputs, and this is the headline figure for the scenario.
  • Calculated sample works out to 145 samples at these inputs.
  • Minimum sample size works out to 50 samples at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where sampling rate sits at 10% and the headline result is 200 samples, this scenario comes in 27.5% below the baseline at 145 samples.
  • The practical read: the gap between this scenario and the baseline is entirely attributable to sampling rate, so recovering it is worth quantifying in dollars before considering equipment or staffing changes. A flat percentage rule is not statistically equivalent to a standard AQL plan; for contractual acceptance sampling, derive sample size and accept/reject numbers from ANSI/ASQ Z1.4 or similar.

Results at a glance

  • Required sample size: 145 samples (headline result)
  • Calculated sample: 145 samples
  • Minimum sample size: 50 samples

Run it with your numbers

  • To rerun this with your own numbers, open the live Sampling Plan Size calculator, set sampling rate to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.