Resin calculator
How much epoxy does your pour need? Enter your mold size (or volume), pieces and mix ratio, and get resin and hardener amounts in fluid ounces and milliliters, waste buffer included.
Dimensions assume a rectangular mold (length × width × depth; 1 cu in = 0.554 fl oz). For irregular molds, fill one with water, pour it into a measuring cup, and use the volume mode. The buffer covers the resin that stays in the cup and on the stir stick: 10% is realistic.
Your pour
Know what every cast costs
Keepsel turns this pour into a recipe (resin, pigment and hardware) and shows your true cost and margin on every piece you cast.
Start free for 30 daysResin pour math, explained
How much resin do I need for my mold?
For a rectangular mold: length × width × depth in inches, times 0.554, gives fluid ounces. A 4×4×1 inch mold needs about 8.9 fl oz of mixed resin. For irregular molds, fill one with water and measure it: water volume equals resin volume.
How do I split resin and hardener for a 2:1 ratio?
Divide the total by three: two parts resin, one part hardener. For 30 fl oz of mixed resin at 2:1 you'd measure 20 oz of resin and 10 oz of hardener. Always use your brand's stated ratio, and measure by volume unless the maker specifies weight.
Should I measure epoxy by weight or volume?
Most craft epoxies specify their ratio by volume, and resin and hardener have different densities, so a 1:1 volume ratio is usually NOT 1:1 by weight. Follow your manufacturer's instructions; when in doubt, measure by volume in marked cups.
How much extra resin should I mix for waste?
About 10% covers what stays in the cup, on the stir stick, and small overpours. Intricate or multi-part pours waste more. Mixing slightly over beats stopping mid-pour to mix again: partial second batches are where curing problems start.
What happens if I get the resin ratio wrong?
Off-ratio epoxy cures soft, sticky or not at all, and there's no fixing it after the pour. Measure carefully in marked cups, scrape thoroughly while mixing, and when a piece matters, do a small test pour with any new resin brand first.
Also useful: the free handmade pricing calculator for what each cast costs and earns. And see how Keepsel runs a whole resin business.
Stop pouring your margin into the cup
Keepsel keeps this as your piece's recipe: every cast you log draws down resin, pigment and hardware, and shows your true cost and margin per piece.
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