Free resin and epoxy cost calculator. Enter mold dimensions (rectangular or cylinder), resin price per gallon, density, waste percentage, additives, and amortized mold cost; outputs the exact volume, weight, and total cost per pour.
Built and maintained by Paul Clark, Redmoon Software · Changes and corrections
Use before pricing a resin piece for sale, or when comparing whether a cheaper bulk resin or a different mold-amortization schedule meaningfully changes your per-piece cost.
Like the 3D Print Cost & Profit Estimator, this converts a physical volume into a material cost, but resin's waste percentage and mold amortization play the role that 3D printing's failure buffer and printer wear play.
This pour needs about 13.7 fl oz of mixed resin.
Volume is computed from mold dimensions — length × width × depth for rectangular molds, or π × (diameter ÷ 2)² × depth for cylinders — converted from cubic inches to gallons by dividing by 231.
A waste/cure-loss percentage is added on top to cover mixing cup residue and stir-stick drag, then converted to weight using resin density in lb/gallon.
Total cost = resin cost (volume × price per gallon) + flat additive/pigment cost + mold cost amortized over its expected number of uses.
Fill the empty mold with water and measure the poured volume in a graduated cup, or use the dimension formula this calculator applies — length × width × depth for rectangular molds, or π × (diameter ÷ 2)² × depth for cylinders.
Mixing cup residue, stir-stick drag, and trimmed overflow all add loss beyond the mold's exact volume. The waste/cure-loss percentage field bakes that overage into the total.
The mix ratio doesn't change the poured volume, but different ratios come in differently sized part-A/part-B bottles, which can shift your effective price per gallon — enter the actual price you pay per gallon of combined mixed resin.
Input
Rectangular mold 6" × 4" × 1", $45/gallon resin, 9.1 lb/gal density, 3% waste, $1.50 additive, $20 mold amortized over 50 uses.
Output
Volume 0.107 gal (24 in³) → total cost $6.72.
24 cubic inches converts to 0.104 gallons, plus 3% waste brings it to about 0.107 gallons weighing roughly 0.97 lb. Resin cost is $4.82, plus $1.50 additive and $0.40 mold-per-use ($20 ÷ 50 uses), for a total pour cost of about $6.72.
Price per gallon is the obvious input and often not the largest on small pieces. Mixing cups, stir sticks, gloves, release agent and sanding supplies are consumed on every pour, and silicone molds wear out, which is what the mold-uses field spreads across each pour.
Cup residue behaves like a fixed amount per mix rather than a percentage, so small pours waste a far larger share than the default 3% suggests. Pouring several pieces from one mix is the cheapest fix. Demolding, sanding and polishing are real labour on every piece, and this calculator does not count them.
A pour that cures with bubbles, soft spots or a leak is consumed in full, so the cost per sellable piece is the cost per pour divided by your success rate. Leaking molds and inserts also change the volume, so measure the real fill rather than trusting the outside dimensions.
Uncured resin is a sensitiser and an irritant, and repeated skin exposure can produce an allergy that ends the hobby. Leftover mixed resin should be left to cure fully before it goes in the bin, never poured down a drain. None of that is a cost line, but it is the part of the process that most affects whether it is worth doing at home.
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