Injection Molding worked example

Plastic Part Weight with part volume from cad of 9 cc: a worked example

This worked example runs the plastic part weight numbers for a tougher week than the baseline: part volume from cad of 9 cc instead of the typical 18 cc. Estimate part weight from CAD volume and resin density for shot sizing and cost estimating before mold trials.

The inputs for this scenario

  • Part volume from CAD: 9 cc (the input this scenario stresses; the baseline uses 18)
  • Resin density (specific gravity): 1.04 g/cc (held at the documented default)
  • Packing factor: 1.03 x (held at the documented default)

Working through the calculation

  • The calculation starts from the formula this tool documents: Part weight = Volume x Density x Packing factor.
  • Result works out to 9.64 g at these inputs, and this is the headline figure for the scenario.
  • Volume x Density (unfactored) works out to 9.64 value at these inputs.
  • Multiplier works out to 1 x at these inputs.
  • Factor A x B works out to 9.36 value at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where part volume from cad sits at 18 cc and the headline result is 19.28 g, this scenario comes in 50% below the baseline at 9.64 g.
  • Use it during design and quoting, before a mold trial, to drive shot size, resin cost, and press selection. 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

  • Result: 9.64 g (headline result)
  • Volume x Density (unfactored): 9.64 value
  • Multiplier: 1 x
  • Factor A x B: 9.36 value

Run it with your numbers

  • To rerun this with your own numbers, open the live Plastic Part Weight calculator, set part volume from cad to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.