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Epoxy river table calculator
Enter the size of the gap you plan to fill, a waste allowance and the maximum pour depth on your epoxy's data sheet to see how much to buy and how many pours it takes.
How to use this calculator
Epoxy for a river table or a resin fill is a volume calculation: length × average width × depth. The calculator works in cubic inches (or converts millimeters to inches in metric mode) and divides by 231, the number of cubic inches in a US liquid gallon, then converts to liters at 3.785 liters per gallon. A 72-inch river averaging 8 inches wide and 1.75 inches deep holds 72 × 8 × 1.75 = 1,008 cubic inches, about 4.4 gallons.
Rivers are rarely straight, so measure the width at several points along the live edges and use the average. If the slab sits in a mold with a gap underneath, or you plan a flood coat over the whole top, add that volume too. The waste allowance covers resin left in mixing buckets, leaks through the mold and the overfill that gets flattened off later. The 15% default is a planning assumption; a well-sealed mold needs less.
The most important number here is the maximum pour depth. Epoxy gives off heat as it cures, and a thick mass of resin can overheat. Deep-pour casting resins are formulated for thicker layers than coating epoxies, but every product has its own limit, mix ratio and recoat window. Enter the maximum depth printed on your product's technical data sheet, and the calculator tells you how many layers your depth needs. The data sheet, not this page, is the final word.
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Questions about this calculator
How much does the epoxy for a river table cost?
Multiply the gallons to buy by the price of your chosen deep-pour epoxy. Resin is often a large share of a river table's material cost, which is why makers ask for the river's size before they quote.
Can I pour it all in one go?
Only if your depth is within the product's maximum pour depth. Deeper than that, pour in layers and follow the recoat window on the data sheet.