How to use this calculator
Measure the inside length and width of a rectangular mold and your intended pour depth. Enter the mixed-product density from supplier documentation if you want a mass estimate. Include an allowance for cup residue or spills.
The formula
A worked example
A 30 × 20 × 0.5 cm casting is 300 mL. With 10% extra, prepare 330 mL of mixed resin. At 1.1 g/mL, that mixture has a mass of 363 g.
Assumptions & limitations
Calculates total mixed quantity only. Does not determine resin-to-hardener ratios, allowable pour depth, curing conditions, or material compatibility. Density varies by product; the default is an example.
Common questions
Can I split this result equally between resin and hardener?
Only if the product explicitly requires that ratio on the same measurement basis. Weight and volume ratios can differ.
What about objects embedded in the mold?
Subtract their displacement from the geometric volume separately; this tool assumes an empty mold.
Supporting reference
The method above states this calculator’s assumptions. This reference provides related definitions and technical context.
WEST SYSTEM: epoxy user manual ↗Formula and worked example checked against automated test cases. About our methodology.