Injection Molding calculator

Shot Size Calculator

Calculate total shot size from part weight, cavity count, runner weight, and cushion factor. Multiply the inputs together with a multiplier for unit conversion or scaling.

What this calculator does

  • Calculate total shot size from part weight, cavity count, runner weight, and cushion factor.
  • Use it when shot size in injection molding needs a few factors combined into one defensible number for injection molding.
  • Turns shot size base quantity, shot size multiplier, shot size conversion or loss factor into a result for shot size in injection molding.

Formula used

  • Shot size result = shot size base quantity × shot size multiplier × shot size conversion or loss factor × shot size planning multiplier
  • Use the planning multiplier for mix, contingency, or unit conversion only.

Inputs explained

  • Shot size base quantity: Enter the main quantity, demand, area, population, or count from the source record.
  • Shot size multiplier: Enter the applicable rate, units per assembly, cavities, positions, or events per item.
  • Shot size conversion or loss factor: Use the conversion, loss, efficiency, scrap, or scaling factor that applies to the calculation.
  • Shot size planning multiplier: Use a final multiplier for model mix, planning factor, contingency, or unit conversion.

How to use the result

  • Use it when shot size in injection molding is being combined into a single number.
  • Order of operations and unit alignment matter; this is a simple product, not a unit-aware engine.

Common questions

  • What does the shot size calculator give me? Calculate total shot size from part weight, cavity count, runner weight, and cushion factor. You get a result you can defend before quoting, scheduling, or sign-off.
  • What numbers should I focus on first? shot size base quantity, shot size multiplier, shot size conversion or loss factor usually move the result most. Pull from measured injection molding runs, supplier data, and recent quotes rather than memory.
  • How should I use the result? Use the result as the input to the next injection molding step or quote line.
  • What can throw the result off? Confirm units before you read the number; an off-by-1000 unit error is the usual cause of bad results.

Last reviewed 2026-05-12.