Plastic Shrinkage Calculator
Calculate mold cavity dimensions from finished part size and material shrinkage rate to ensure correct part dimensions.
Inputs
mm
mm
mm
%
Results
Cavity Length
152.25 mm
Cavity Width81.2 mm
Cavity Depth25.38 mm
Length Oversized By2.25 mm
Width Oversized By1.2 mm
Depth Oversized By0.38 mm
Volumetric Shrinkage4.37%
Cavity Volume313.7 cm³
Total Shrinkage3.83
How to Use This Calculator
- Enter the desired finished part dimensions (length, width, depth in mm).
- Set the material shrinkage rate (%) from the resin datasheet — typically 0.5–3%.
- Review cavity dimensions (enlarged by the shrinkage factor) to machine into the tool steel.
- Use the length, width, and depth growth values to adjust your CAD cavity model before machining.
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