Thermoforming & Vacuum Formed Products worked example

Stack Height at 65% line efficiency: a worked example

Here is what the math looks like when conditions slip. We hold every other input steady and drop line efficiency to 65%, then walk the calculation through step by step. Stack Height turns a run's total part count and runtime into an effective per-hour throughput, discounted by how efficiently the line actually ran.

The inputs for this scenario

  • Parts formed over the run: 1,200 units (held at the documented default)
  • Line runtime: 8 hr (held at the documented default)
  • Line efficiency: 65 % (the input this scenario stresses; the baseline uses 90)

Working through the calculation

  • The calculation starts from the formula this tool documents: Raw stack height = completed output ÷ runtime.
  • Effective throughput works out to 97.5 units at these inputs, and this is the headline figure for the scenario.
  • Raw throughput works out to 150 units at these inputs.
  • Efficiency works out to 65 % at these inputs.
  • Runtime works out to 8 hr at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where line efficiency sits at 90% and the headline result is 135 units, this scenario comes in 27.78% below the baseline at 97.5 units.
  • The practical read: the gap between this scenario and the baseline is entirely attributable to line efficiency, so recovering it is worth quantifying in dollars before considering equipment or staffing changes. It bundles all losses into one efficiency figure, so it won't tell you whether the shortfall came from micro-stops, speed loss, or downstream stacking jams — use it for rate-setting, not root-cause diagnosis.

Results at a glance

  • Effective throughput: 97.5 units (headline result)
  • Raw throughput: 150 units
  • Efficiency: 65 %
  • Runtime: 8 hr

Run it with your numbers

  • To rerun this with your own numbers, open the live Stack Height calculator, set line efficiency to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.