Resin Volume for Molds
Calculate the exact amount of epoxy resin needed for rectangular, cylindrical, or dome molds, with shrinkage and mix ratio corrections.
Results
What is it?
Resin casting requires measuring exact volumes of Part A (resin) and Part B (hardener) and mixing them at the ratio specified by the manufacturer. Under- or over-pouring leads to sticky uncured resin. Shrinkage during cure means you need slightly more resin than the mold volume. Volume formulas: rectangular = L x W x H; cylinder = pi x (D/2)^2 x H; hemisphere = (2/3) x pi x (D/2)^3.
How to use
Select your mold shape and enter dimensions in centimeters. Enter the shrinkage percentage (5% is safe for most epoxies) and your product mix ratio. The calculator outputs total resin needed and the exact Part A and Part B amounts to measure.
Example scenario
10 x 8 x 3 cm rectangular mold: raw volume = 240 mL. With 5% shrinkage: 252 mL total. At 1:1 mix ratio: 126 mL Part A + 126 mL Part B.
Pro tip
Always measure resin by volume using graduated mixing cups — weight-based mixing only works if you know each component density. Mix slowly for at least 3-5 minutes, scraping sides and bottom. Pour slowly to minimize bubbles. A heat gun or torch passed briefly over the surface removes surface bubbles. Work in a warm room (20-25°C) for best results — cold temperatures dramatically slow cure time.