Municipal Waste Sorting Equipment worked example

Screen Efficiency at 65% target screen efficiency: a worked example in municipal waste sorting equipment

Suppose target screen efficiency falls to 65%. This page works the full calculation at that level so you can see exactly which result moves and by how much. Estimate the screening efficiency of a trommel, disc, or ballistic screen and see how far it sits from the design target.

The inputs for this scenario

  • Undersize correctly passed to unders: 210 kg (held at the documented default)
  • Total undersize present in feed: 250 kg (held at the documented default)
  • Target screen efficiency: 65 % (the input this scenario stresses; the baseline uses 90)

Working through the calculation

  • The calculation starts from the formula this tool documents: Screen efficiency = undersize correctly passed / total undersize in feed x 100.
  • Screen efficiency works out to 84 % at these inputs, and this is the headline figure for the scenario.
  • Gap to target screen efficiency works out to -19 points at these inputs.
  • Undersize correctly passed works out to 210 count at these inputs.
  • Total undersize in feed works out to 250 count at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where target screen efficiency sits at 90% and the headline result is 84 %, this scenario lands almost exactly on the baseline at 84 %.
  • It computes screen efficiency as undersize correctly passed divided by total undersize in the feed, and the point gap to your target. 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

  • Screen efficiency: 84 % (headline result)
  • Gap to target screen efficiency: -19 points
  • Undersize correctly passed: 210 count
  • Total undersize in feed: 250 count

Run it with your numbers

  • To rerun this with your own numbers, open the live Screen Efficiency calculator, set target screen efficiency to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.