Resin Mold Volume Calculator
Calculate the resin volume and weight a mold needs from its shape and size, with a top-up margin so you never mix a short batch.
How it works
Box = L × W × D · Cylinder = π(D÷2)² × H · Sphere = 4/3 π(D÷2)³ · Resin = volume × (1 + margin) · Weight = volume × density
Resin fills a mold by volume, and 1 cm³ equals 1 mL, so the geometry of the cavity is all you need — a box is length × width × depth, a cylinder is π r² × height, and a sphere is 4/3 π r³. Because leftover mixed resin cannot be saved and a short pour ruins a piece, always prepare a margin above the exact volume. Multiplying by the resin density converts the volume to the grams you weigh out, which matters when your two parts are measured by weight rather than volume.
Worked example
A 10 × 6 × 3 cm box mold has a volume of 180 cm³. Adding a 10% margin gives 198 cm³, which is 198 mL of resin. At a density of 1.1 g/cm³ that is about 218 g to weigh out and mix.
Frequently asked questions
Should I mix by volume or weight?
Follow your resin brand — most casting epoxies specify a mix by weight for accuracy, while some are 1:1 by volume. This calculator gives both mL and grams so you can measure whichever your product requires.
Why add a top-up margin?
Resin coats the mixing cup, some clings to the mold walls, and deep pours can need a small top-up as they settle. A 5–15% margin avoids the disaster of running out with an unfillable cavity.
Does this include embedded objects?
No — it assumes an empty cavity. If you are embedding items, subtract their volume, or simply pour, place the object, and top up to the rim.
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This calculator is for educational purposes. Double-check important results before acting on them.