How this epoxy calculator works
Epoxy is bought by liquid volume, so the calculator multiplies the length, width and depth of your pour to get cubic inches or cubic centimeters, converts to fluid ounces or milliliters, and adds a small overage. Some resin always stays in the mixing cup and on the stir stick, and running out mid-pour ruins the piece — 5–10% overage is standard practice.
Measuring a river table channel
For a river table, measure only the channel — not the whole slab. Use the average width if the live edge varies: measure the gap at several points and take the mean. Depth is the slab thickness. If the channel narrows and widens a lot, split it into sections, calculate each and add them up. Seal the wood with a thin coat first, or bubbles will rise into your main pour.
Which resin for which depth?
Standard tabletop epoxy is designed for thin layers, typically up to about ¼ inch (6 mm) per pour — pour it deeper and the exothermic reaction can overheat, yellow and crack. Deep pour (casting) resins accept 2 inches (5 cm) or more per layer, but cure slowly. For a typical river table, use deep pour resin for the channel and finish with a tabletop flood coat.
Mixing tips
Measure resin and hardener by the ratio on the label — most casting resins are 1:1 or 2:1 by volume. Mix slowly for a full 3–5 minutes, scraping the sides and bottom, then pour through a clean cup ('double cup' method) to avoid unmixed streaks. Warm resin (around 75°F / 24°C) mixes and degasses far better than cold.