Measure Your Mold
Enter inside dimensions of your mold or void. For river tables, measure the channel length, width, and depth.
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An epoxy resin calculator determines exact resin and hardener volumes for rectangular and cylindrical molds at any mix ratio. Enter mold dimensions, number of pour layers, and colorant load percentage to get fluid ounces needed, with warnings for exothermic risk in deep pours.
Mold & Mix Settings
Typical: 2–6%. Max 10% (IFRA)
Add 5–10% for mixing losses
Deep pours generate heat — exceeding max depth risks cracking
Mix Results
Total Volume
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Resin
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Hardener
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Colorant
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Pour Layers
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Est. Cost
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Volume Breakdown
Enter mold dimensions and hit Calculate to see the volume breakdown.
How It Works
Set Your Ratio
Select your resin's mix ratio (check the label). Most art resins are 1:1, deep pour resins are often 2:1 or 3:1.
Add Colorant
Set your pigment or dye percentage. Stay under 10% total load to avoid cure inhibition. Most mica powders work at 2–6%.
Mix & Pour
Get exact fluid ounces for resin and hardener. For deep pours, the layer calculator tells you exactly how much per pour.
Why Exact Resin Measurement Matters
Epoxy resin is an exothermic chemical reaction — the ratio between resin and hardener must be exact or the cure fails. Too much hardener and it cures rubbery. Too little and it stays sticky forever. For deep pours, exceeding the manufacturer's maximum depth generates dangerous heat that can crack, yellow, or even smoke. ResinRatio calculates your mold volume to the fluid ounce, splits it by your exact mix ratio, and warns you if your pour depth exceeds safe limits. Every calculation runs in your browser — your project dimensions never leave your device.
Frequently Asked Questions
How do you calculate epoxy resin volume for a mold?
For rectangular molds: Volume = Length × Width × Depth. For cylindrical molds: Volume = π × Radius² × Depth. Convert cubic inches to fluid ounces by multiplying by 0.554. Then split the total volume by your resin's mix ratio (typically 1:1 or 2:1 by volume). Always add 10% extra to account for mixing cup waste and overflow.
Why does epoxy resin crack in deep pours?
Epoxy generates heat (exotherm) as it cures. In deep pours, heat cannot escape fast enough, causing the internal temperature to spike — sometimes above 400°F. This thermal stress causes cracking, yellowing, and warping. Deep-pour epoxy formulas are designed for maximum 2" layers, and even then, ambient temperature must be below 77°F.
What is pot life and why does temperature matter?
Pot life is the working time after mixing resin and hardener before it begins to gel. Higher temperatures dramatically shorten pot life — a resin with 45-minute pot life at 72°F may only last 20 minutes at 85°F. In hot conditions, mix smaller batches, work in air conditioning, and avoid leaving mixed resin sitting in the cup.