Free tool

Shrinkage Calculator

How much oversize must the cavity be cut for the part to shrink onto dimension? Enter the target part dimension or the machined cavity dimension and pick a material. The shrinkage ranges follow our mould shrinkage guide.

Target part dimension: 80.00 mm Machined cavity dimension: 80.00 mm Material Glass-fibre grades shrink anisotropically — typically 2–3× more across the flow direction than along it. Critical dimensions in flow and cross-flow may need different shrinkage values.

Required cavity dimension 80.44 mm

Cavity range (low–high shrink)80.32 mm – 80.56 mm

Shrinkage used0.4–0.7 %

Predicted part dimension 79.56 mm

Part range (low–high shrink)79.44 mm – 79.68 mm

How to use the result

The cavity is cut oversized by the shrinkage factor: D cavity = D part / (1 − s). Where the true value lands inside the material range depends on wall thickness, gate position, packing and mould temperature — the same process window that sets achievable tolerances. For critical fits, machine steel-safe and correct after first-article measurement; the background is in our mould shrinkage guide.

Shrinkage ranges are typical mould shrinkage values for unfilled grades under normal process conditions, from published datasheets. Real shrinkage varies with wall thickness, gate size, packing pressure and mould temperature. Values are planning figures for tool design — final cavity corrections are made after first-article inspection.

Need shrinkage applied to your drawing? Send Nordmould your 3D model — our tooling partners cut cavities with material-specific shrinkage and correct them at first article.