Environmental Test Chambers & Reliability Labs worked example

Sample Size Planning with qualification lots or builds of 1.5 lots: a worked example

Suppose qualification lots or builds falls to 1.5 lots. This page works the full calculation at that level so you can see exactly which result moves and by how much. Plan reliability lab sample count from qualification lots, stress cells per lot, and samples per stress cell.

The inputs for this scenario

  • Qualification lots or builds: 1.5 lots (the input this scenario stresses; the baseline uses 3)
  • Stress cells per lot: 6 cells / lot (held at the documented default)
  • Samples per stress cell: 12 samples (held at the documented default)

Working through the calculation

  • The calculation starts from the formula this tool documents: Total planned samples = qualification lots × stress cells per lot × samples per stress cell.
  • Total reliability test samples works out to 108 samples at these inputs, and this is the headline figure for the scenario.
  • Estimated sample handling hours works out to 5.4 hr at these inputs.
  • Qualification lots or builds works out to 6 lots at these inputs.
  • Samples per stress cell works out to 12 samples at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where qualification lots or builds sits at 3 lots and the headline result is 216 samples, this scenario comes in 50% below the baseline at 108 samples.
  • It computes the total number of test samples a qualification consumes by multiplying lots, stress cells per lot, and samples per cell, and estimates the associated handling hours. When the numbers land here, the stressed input is the lever to work; the walkthrough above shows exactly how much each output recovers as it climbs back toward the baseline.

Results at a glance

  • Total reliability test samples: 108 samples (headline result)
  • Estimated sample handling hours: 5.4 hr
  • Qualification lots or builds: 6 lots
  • Samples per stress cell: 12 samples

Run it with your numbers

  • To rerun this with your own numbers, open the live Sample Size Planning calculator, set qualification lots or builds to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.