Why Use This Calculator?
Epoxy is priced like perfume and mixed like pancake batter — and running short mid-pour ruins the whole table. This calculator converts your mold dimensions into US gallons, subtracts the wood volume for river tables, and adds the 10% that always sticks to the mixing cup.
For a river table, enter the full mold size and estimate the wood's cubic inches (length × width × thickness of the slab). The tool nets it out so you buy what the river actually needs, not what the whole box holds.
How It Works
- Measure the inside dimensions of your mold or form.
- Estimate wood displacement for river pours — zero for flat coatings.
- Buy the calculated gallons; deep pours need slow-cure resin in layered passes.
Frequently Asked Questions
How much resin do I need for a river table?
Multiply the mold's internal volume and subtract the wood's displacement, then add ~10% for mixing loss. A 72 × 18 × 1.5-inch mold with a 600-cubic-inch slab nets about 7.6 gallons — the calculator runs this exact path.
Can I use this as an epoxy calculator for a bar top or countertop?
Yes — for thin coating coats, enter the full surface and a small depth (a 1/16-inch coat is depth 0.0625). Multiple thin coats beat one thick flood on flat surfaces.
How deep can I pour epoxy at once?
Most casting resins cap at 2 inches per pass or heat and crack; deep pours need slow-cure casting resin in layers, waiting 4–8 hours between passes.
Tips & Things to Watch
- Mix by volume or weight exactly as your resin's datasheet says — ratios are not universal.
- Seal coats first: a thin coat over porous wood stops bubbles in the deep pour.
- Room temperature matters — cold resin stays thick and traps bubbles.