Casting Resin Calculator
Calculate the resin volume a mould needs and split it into parts A and B.
Last updated · View algorithm, constants and default inputs (JSON)
About this calculator
Estimate the mix volume for one or more moulds. Enter each mould’s measured capacity and the exact manufacturer mix ratio by volume; ratios given by weight cannot be used without density conversion. The added volume percentage is a user-selected planning allowance, not a claim about how much every resin shrinks. Follow product instructions for mixing and pour depth.
Worked example
calculated with the default values below
Mould volume 500 ml · Number of moulds or pours 1 · Part A volume parts 1 · Part B volume parts 1 · Extra volume allowance 3 % · Price per litre of kit 30 $ Total resin needed 515.0 ml · Total resin needed 0.515 l · Part A 257.5 ml · Part B 257.5 ml · Resin cost 15.45 $ · Cost per mould 15.45 $
General background references
Disclaimer
These calculators provide planning estimates only. Building codes, wiring regulations and safety requirements differ by country and change over time, and nothing here replaces a licensed professional or a permit. For structural, electrical or gas work, follow local code and have the installation inspected.
Implementation source
This record describes the implementation used by this page. It is not independent validation. External references, when available, support only the stated formula or definition; estimates and custom rules retain their own assumptions.
Formula and variables
Vₜ = V×N×(1+s÷100); A = Vₜ×a÷(a+b); C = Vₜ÷1000×p
- V
- Mould volume (mL)
- N
- Number of moulds
- s
- Shrinkage allowance (%)
- a
- Part A ratio
- b
- Part B ratio
- Vₜ
- Total mix volume (mL)
- A
- Part A amount (mL)
- C
- Total cost
- p
- Kit price per litre
A:B parts are by volume and must match the product label. A weight ratio needs density conversion; defaults are examples.
Frequently asked questions
Why add an extra volume allowance?
The percentage increases the measured mould volume for planning convenience; it is not a universal resin-shrinkage value. Enter the exact manufacturer mix ratio by volume. If the label gives a weight ratio, density conversion is needed. The calculator does not determine pour depth or curing requirements.