Municipal Waste Sorting Equipment worked example

Contamination Rate at 3.6% specification or broker target contamination: a worked example

This worked example runs the contamination rate numbers for a tougher week than the baseline: 3.6% specification or broker target contamination instead of the typical 5%. Estimate the contamination rate in an outbound bale or sampled stream and see how far it sits from the broker or specification target.

The inputs for this scenario

  • Out-throw and prohibitive weight in sample: 8 kg (held at the documented default)
  • Total sampled bale or stream weight: 250 kg (held at the documented default)
  • Specification or broker target contamination: 3.6 % (the input this scenario stresses; the baseline uses 5)

Working through the calculation

  • The calculation starts from the formula this tool documents: Contamination rate = out-throw weight / total sampled weight x 100.
  • Contamination rate works out to 3.2 % at these inputs, and this is the headline figure for the scenario.
  • Gap to specification works out to 0.4 points at these inputs.
  • Out-throw weight works out to 8 count at these inputs.
  • Total sampled weight works out to 250 count at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where specification or broker target contamination sits at 5% and the headline result is 3.2 %, this scenario lands almost exactly on the baseline at 3.2 %.
  • Use it on every QC bale audit, before shipping to a new buyer, or when a mill flags a load. A result at this level usually justifies acting on the stressed input before touching anything else, because every other figure in the table is downstream of it.

Results at a glance

  • Contamination rate: 3.2 % (headline result)
  • Gap to specification: 0.4 points
  • Out-throw weight: 8 count
  • Total sampled weight: 250 count

Run it with your numbers

  • To rerun this with your own numbers, open the live Contamination Rate calculator, set specification or broker target contamination to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.