Resin Calculator
Enter your mold dimensions and mix ratio to get exactly how much epoxy resin and hardener to mix.
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Why a Waste Buffer Matters
Pouring epoxy resin is not a zero-loss process — some sticks to your mixing cup, some clings to the stir stick, and mold shapes that aren't a perfect rectangular block hold slightly less than the simple length × width × depth math suggests. Calculate exactly what the mold holds with no margin, and it's common to come up just short at the end of a pour, which is a much bigger problem with resin than with most craft materials since you can't easily "add a bit more" to an already-curing pour without visible layering.
How to Use This Calculator
Measure your mold's internal length, width, and how deep you plan to fill it (not the mold's total depth if you're not filling it to the top). Keep the default 10% waste buffer unless you have a specific reason to change it, and select your product's mix ratio — check the label, since resin/hardener ratios vary by brand and product line.
How We Calculate It
Raw volume (cubic inches) = length × width × depth. Total needed = raw volume × (1 + waste buffer), converted to fluid ounces by dividing by 1.80469. That total is then split according to your mix ratio — for a 2:1 ratio, resin gets 2/3 of the total volume and hardener gets 1/3.
A Few Notes
This calculates by volume, which is how most mix ratios are specified — but resin and hardener usually have different densities, so a 1:1 ratio by volume is not 1:1 by weight. If your product's instructions specify the ratio by weight instead of volume, use a scale and follow that specification directly rather than this calculator's volume split, since mixing on the wrong basis can leave a cast sticky or permanently uncured.