River Table Epoxy Calculator
Enter the size of the channel between your slabs. The calculator averages the width, multiplies by length and depth, and adds an allowance for waste.
How the calculation works
A river is rarely a perfect rectangle, so the calculator uses the average of the narrowest and widest measurements:
Volume = length × ((narrow width + wide width) ÷ 2) × depth × (1 + waste %)
The result is converted to US gallons (231 cubic inches each), US fluid ounces and litres. For example, a 48 in channel that is 4 in wide at one end and 8 in at the other, poured 2 in deep, holds 48 × 6 × 2 = 576 cubic inches. With 10% waste that becomes 633.6 cubic inches, or about 2.74 US gallons.
Tips for pouring a river table
- Use a deep pour epoxy if your channel is thicker than about one inch; split deeper pours into several layers as the manufacturer recommends.
- Seal the wood first with a thin coat of resin so air in the wood does not bubble up into the pour.
- Check the mix ratio on your product (commonly 2:1 or 1:1 by volume). Use the epoxy mixing ratio calculator to split the total into Part A and Part B.
- Your mould must be sealed and level, otherwise the resin will leak or the surface will be uneven and you will use more than calculated.
This calculator gives an estimate. Resin products differ in density, working time and maximum thickness, so follow your manufacturer's data sheet.
Frequently asked questions
How much epoxy do I need for a river table?
Multiply the length of the channel by its average width and by the pour depth to get the volume, then add 10–15% extra for waste, mixing cup residue and wood that soaks up resin. For a channel 48 in long, 6 in wide on average and 2 in deep, that is 576 cubic inches, or about 2.5 US gallons with 10% waste.
How do I measure the width of an uneven river?
Measure the narrowest point and the widest point and average them, or take 3–5 measurements along the channel and average those. The more irregular the edges, the more measurements you should take.
How thick can I pour deep pour epoxy?
It depends on the product. Standard tabletop epoxy is usually limited to about 1/8 to 1/4 inch per pour, while deep pour epoxy is formulated for layers from about 1 to 2 inches or more. Exceeding the limit can overheat the resin and cause cracking or yellowing. Always check the technical data sheet.
Why add extra for waste?
Some resin always stays in the mixing cup and on the stir stick, the mould surface may not be perfectly flat, and live-edge wood has pores and cracks that take in resin. Ten percent is a sensible minimum; use 15% or more if you plan to seal cracks with the same resin.