Resin Pour Calculator
Mixing too little epoxy resin ruins a pour; mixing too much wastes expensive product. This calculator takes the length, width, and depth of a rectangular pour, computes the total volume, adds a waste allowance for what clings to your cup, and splits the result into resin and hardener using your product's exact mix ratio. Outputs are given in both cubic inches and US fluid ounces so you can measure straight from graduated cups. The mix ratio comes from your specific resin label, so set it to match before you pour.
Resin pour formula
Volume (cu in) = length * width * depth
With waste = volume * (1 + waste% / 100)
Total fl oz = with waste / 1.804688
Resin fl oz = total * resin parts / (resin + hardener parts)
Hardener fl oz = total * hardener parts / (resin + hardener parts)
One US fluid ounce equals exactly 1.804688 cubic inches. The waste allowance scales the total up before the resin and hardener split, so both components include their share of the buffer.
Pouring tips
- Mix ratio is product-specific and printed on the label; the calculator default of 2 to 1 is only a starting point.
- Deep pours often need to be done in thin layers to control the exothermic heat; check your product's maximum single-pour depth.
- Measure by the method your label specifies. Volume ratios and weight ratios are not interchangeable.
- Use the U.S. NIST definition of the fluid ounce for unit conversions when measuring.
- Always work in a ventilated space and follow the product safety data sheet.
Resin pour: frequently asked questions
How much resin do I need for a pour?
Volume equals length times width times pour depth. For a rectangular mold of 12 by 8 inches poured 0.5 inch deep, that is 48 cubic inches. One US fluid ounce is 1.804688 cubic inches, so 48 cubic inches is about 26.6 fluid ounces of total mixed resin. This calculator does the conversion for you.
What is the resin to hardener ratio?
Mix ratio is set by your specific product and printed on the label, commonly 1 to 1 or 2 to 1 by volume. Enter the resin parts and hardener parts and the calculator splits the total mixed volume accordingly. Always follow the manufacturer's exact ratio: getting it wrong prevents proper curing.
Should I mix extra resin?
Yes. A small waste allowance covers resin left clinging to the mixing cup and stir stick. Enter a waste percentage, commonly 5 to 10 percent, and the calculator adds it to your total so you do not come up short mid-pour.
Does this work for non-rectangular molds?
This calculator assumes a rectangular pour: length times width times depth. For round or irregular molds, compute the volume separately (for a circle, pi times radius squared times depth) and the resin to hardener split still applies to that total.
Why convert to fluid ounces?
Resin and hardener are usually sold and measured by volume in fluid ounces or milliliters. Converting cubic inches to fluid ounces lets you measure directly with graduated cups. One US fluid ounce equals 1.804688 cubic inches by definition.
Official sources
- National Institute of Standards and Technology: unit conversion factors.
- U.S. Consumer Product Safety Commission: product safety guidance.
Reviewed by the CalculatorHub team, edited by James Graham, 16 June 2026. See our methodology.