Shot Weight Calculator
Estimate total shot weight, recommended shot weight, and machine shot size range for injection molding.
Need Help Selecting the Right Shot Size or Machine?
This calculator provides a quick estimate of shot weight and machine shot size. For real production, factors like material type, runner design, mold structure, and machine capacity can significantly affect the final result.
Our engineering team can help you validate your shot size, optimize mold design, and recommend the right injection molding solution for your project.
Get Expert SupportQuickly estimate shot weight based on part design and mold configuration.
Use this shot weight calculator to estimate material usage and support injection molding planning.
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How to Calculate Shot Weight
Shot weight is calculated based on part weight, number of cavities, and runner system.
Formula:
Shot Weight = (Part Weight × Cavities) + Runner Weight
Recommended Shot Weight = Shot Weight × (1 + Safety Margin)
Example:
If part weight is 25g, cavities = 2, and runner weight = 10g →
Shot Weight = (25 × 2) + 10 = 60g
With a 10% margin → Recommended Shot Weight = 66g
Key Factors Affect Shot Weight
- Part Weight
Directly determines the base material required per cycle.
- Cavities
More cavities increase total shot weight proportionally.
- Runner System
Cold runners increase material usage, while hot runners reduce waste.
- Material Type
Different materials may influence processing conditions and safety margin selection.
- Safety Margin
Helps maintain stable filling and reduces the risk of short shots.
Shot Weight vs Shot Size
Shot weight refers to the actual material weight injected per cycle, while shot size relates to machine barrel capacity.
Shot weight is used for material estimation, while shot size is used for machine matching and selection.
FAQ
How to calculate shot weight in injection molding?
Multiply part weight by cavities and add runner weight, then apply a safety margin.
What affects shot weight the most?
Part weight, number of cavities, runner design, and safety margin.
Is this calculator accurate?
It provides an engineering estimate; actual results depend on mold design, material type, and processing conditions.
What is a typical shot weight range?
It varies widely depending on part size, cavity count, and runner system.
Can this be used for all materials?
Yes, but actual production results may vary based on material behavior and mold conditions.
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