Resin Volume Calculator

Why Getting the Volume Right Matters

Running out of mixed epoxy mid-pour is one of the most frustrating problems in resin crafting. Epoxy cures by a chemical exothermic reaction — adding a fresh batch on top of a partially cured surface creates a heat differential that can cause delamination, soft spots, and permanent colour mismatch. On the other hand, mixing far more than you need wastes money and creates disposal headaches, especially for high-viscosity casting resins sold in limited volumes.

The calculator above uses the straightforward formula: Volume = Length × Width × Depth. It then adds a configurable waste factor (default 10%) to account for resin that sticks to mixing vessels, drips down the sides of your mold, or is left in the container after pouring. For irregularly shaped molds — silicone jewelry molds, river channel voids, curved coaster molds — measure the widest and deepest points and add 15–20% waste to be safe.

Understanding Kit Sizes

Epoxy resin kits are sold by combined volume (Part A + Part B together). A "16 fl oz kit" gives you roughly 8 oz of resin + 8 oz of hardener for a 1:1 ratio product, yielding about 14–15 fl oz after accounting for mixing losses. Manufacturers typically list coverage in square feet at a specific depth (usually ⅛ inch / 3 mm for table-top resins) which can be confusing. This calculator converts your mold dimensions to a raw volume so you can match it directly to a kit label.

Quick Kit-Size Reference

• Under 8 fl oz (240 ml): Small jewelry or coaster kit. Ideal for pendants, dice, small coasters.
• 8–32 fl oz (240–950 ml): Standard table-top kit. Good for tumblers, small trays, resin art panels.
• 32–128 fl oz (1–4 L): Medium project kit. Covers most bar-top and table-top pours up to ½ inch deep.
• 128 fl oz – 1 gal (4–3.8 L): Large kit. River table channels, countertops, and deep-pour base layers.
• Over 1 gal: Professional / contractor supply. For river tables, floor coatings, and bulk production.

Deep-Pour vs Table-Top Formulas

Not all resins can be poured at any thickness. Standard table-top epoxies (ArtResin, TotalBoat Table Top) max out at ¼ inch (6 mm) per layer before generating dangerous exothermic heat. Deep-pour formulas (like those used for river tables) are designed for 2–4 inch (50–100 mm) single pours and have a much slower cure cycle (24–72 hours vs 12–24 for table-top). If your depth exceeds ¼ inch, always reach for a deep-pour product. Our best deep-pour epoxy guide covers the top products by max pour depth, working time, and cost per ounce.

Measurement Tips for Common Project Types

• Coasters & small trays: Measure the interior cavity. Silicone molds often list dimensions on the packaging — use those directly and add 5% waste.
• River tables: The "mold" is the channel between the two slabs. Measure channel length, average channel width, and intended pour depth. Add 20% waste since uneven slab edges lose resin at the sides.
• Tumblers: Use a cylinder volume formula (π × r² × h). A standard 20 oz stainless tumbler is approximately 8 fl oz of exterior surface coating at 1/16 inch thick.
• Countertops: Measure L × W × pour thickness (usually 1/8 inch for a single table-top layer). A 36 × 96 inch countertop at 1/8 inch needs roughly 256 fl oz (2 gal).

How to Use This Calculator

1. Choose inches or centimetres with the toggle above.
2. Enter the mold's length, width, and depth. For irregular molds use the largest cross-section.
3. Adjust the waste factor — 10% for clean rectangular molds, up to 20% for complex shapes.
4. Hit Calculate. The result shows net volume, total needed including waste, and a recommended kit-size band.
5. Cross-reference with the product's stated coverage or use our pressure pot guide to check whether your pour depth requires pressure casting.