Blow Molding & Hollow Plastic Products worked example

Shot Weight with resin weight per cavity of 14 g: a worked example

This worked example runs the shot weight numbers for a tougher week than the baseline: resin weight per cavity of 14 g instead of the typical 28 g. Estimate total shot or drop weight for injection blow, stretch blow, or extrusion blow molded containers from preform or parison weight, cavities, and allowance.

The inputs for this scenario

  • Resin weight per cavity: 14 g (the input this scenario stresses; the baseline uses 28)
  • Active cavities per shot: 8 cavities (held at the documented default)
  • Shot allowance multiplier: 1.05 x (held at the documented default)
  • Unit conversion multiplier: 1 x (held at the documented default)

Working through the calculation

  • The calculation starts from the formula this tool documents: Cavity resin weight per cycle = resin weight per cavity × active cavities per shot.
  • Total shot weight works out to 118 g or lb at these inputs, and this is the headline figure for the scenario.
  • Shot weight before conversion works out to 118 g or lb at these inputs.
  • Unit conversion multiplier works out to 1 x at these inputs.
  • Cavity resin weight per cycle works out to 112 g or lb at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where resin weight per cavity sits at 28 g and the headline result is 235 g or lb, this scenario comes in 50% below the baseline at 118 g or lb.
  • Use it when setting shot size on a new mold, troubleshooting short shots or flash, or estimating resin draw per cycle for cost and capacity planning. 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

  • Total shot weight: 118 g or lb (headline result)
  • Shot weight before conversion: 118 g or lb
  • Unit conversion multiplier: 1 x
  • Cavity resin weight per cycle: 112 g or lb

Run it with your numbers

  • To rerun this with your own numbers, open the live Shot Weight calculator, set resin weight per cavity to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.