Rotational Molding worked example

Resin Cost Per Part at 58% usable resin yield: a worked example in rotational molding

This worked example runs the resin cost per part numbers for a tougher week than the baseline: 58% usable resin yield instead of the typical 80%. Resin Cost Per Part turns polyethylene powder pricing into a defensible per-piece material cost for a rotational molding job.

The inputs for this scenario

  • Parts molded in the run: 100 units (held at the documented default)
  • Resin charge cost per part: 45 $ / unit (held at the documented default)
  • Usable resin yield (net of scrap/flash): 58 % (the input this scenario stresses; the baseline uses 80)
  • Fixed run cost (setup, purge, changeover): 250 $ (held at the documented default)

Working through the calculation

  • The calculation starts from the formula this tool documents: Resin Cost Per Part cost = quantity × rate × capture factor + fixed cost.
  • Weighted cost works out to 2,860 $ at these inputs, and this is the headline figure for the scenario.
  • Per piece value works out to 28.6 $ / piece at these inputs.
  • Captured value works out to 2,610 $ at these inputs.
  • Fixed adjustment works out to 250 $ at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where usable resin yield sits at 80% and the headline result is 3,850 $, this scenario comes in 25.71% below the baseline at 2,860 $.
  • Use it when quoting a rotomolded part or re-costing an existing job after a resin price change. 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

  • Weighted cost: 2,860 $ (headline result)
  • Per piece value: 28.6 $ / piece
  • Captured value: 2,610 $
  • Fixed adjustment: 250 $

Run it with your numbers

  • To rerun this with your own numbers, open the live Resin Cost Per Part calculator, set usable resin yield to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.