Blow Molding & Hollow Plastic Products calculator
Shot Weight Calculator
Shot weight links the resin metering setup to bottle weight, preform weight, neck finish quality, flash, and finished container cost. Tooling and process teams use it to compare cavity layouts, preform weights, and shot-size assumptions before validating a mold or quoting a container.
What this calculator does
- Estimate total shot or drop weight for injection blow, stretch blow, or extrusion blow molded containers from preform or parison weight, cavities, and allowance.
- a blow molding processor needs to estimate total resin shot weight for a bottle, preform, or hollow part mold
- Returns the total resin shot weight represented by the cavity layout and weight assumption.
Formula used
- Cavity resin weight per cycle = resin weight per cavity × active cavities per shot
- Total shot weight = cavity resin weight per cycle × shot allowance multiplier × unit conversion multiplier
Inputs explained
- Shot Weight first factor: undefined
- Shot Weight second factor: undefined
- Shot Weight conversion factor: undefined
- Shot Weight process multiplier: undefined
How to use the result
- Use it for shot-size checks, preform costing, mold cavitation reviews, and resin purchase estimates.
- It does not confirm machine shot capacity, melt cushion, screw recovery, or injection pressure capability; check those on the press or blow molder.
Common questions
- What information do I need for shot weight? Enter resin weight per cavity, active cavity count, process allowance, and conversion multiplier for the shot-weight basis you use.
- Which units should I use? Use one consistent basis for the whole calculation, such as grams, pounds, kilograms, bottles, containers, mold cycles, hours, psi, or dollars. Do not mix grams and pounds or bottles and cases without converting first.
- When is this only an estimate? It does not confirm machine shot capacity, melt cushion, screw recovery, or injection pressure capability; check those on the press or blow molder.
- How can I use the result? Use it to compare cavity counts, select machine capacity, update resin cost, or verify that the shot size is reasonable before a trial.
Last reviewed 2026-05-12.