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Mold & casting calculator

Work out how much resin fills a mold after you subtract what's sitting in it: wood blanks, pen blanks, flowers or any object, as boxes, cylinders or a measured displacement.

1Mold

in
in
in

2Inserts to subtract

Optional

Only count the part of each insert that sits below the fill line. For odd shapes, sink the object in a measuring cup of water and note how much the level rises.

3Buffer and product

Waste buffer
°F
Some limits depend on it, such as GlassCast 50's.
Weight setting
g/mL
Used when the product doesn't publish a liquid density. Clear epoxy is typically about 1.1 g/mL.

Casting tips that change the numbers

  • Mass makes heat. West System notes that 8 fl oz or more of curing epoxy in a cup can get hot enough to melt the cup. Casting resins have their own limits per pour; check the product before a big single pour.
  • Small castings, small batches. Some products set tight limits for small molds: TotalBoat ThickSet allows 2 in deep only with 10 fl oz or less mixed, and TableTop allows 1 in with 6 fl oz or less.
  • Bubbles. A vacuum chamber removes air before pouring; a pressure pot (rated for at least 40–50 PSI, per Alumilite) shrinks bubbles after pouring.