How Much Resin Do You Need for a River Table?

Most river tables take 2 to 10 gallons of epoxy, and you can figure your exact number in about five minutes with a tape measure and one formula.

Getting it right matters. Deep pour epoxy runs $100 to $200 a gallon, so overbuying hurts. Running short is worse: you can't pause a pour halfway and pick it up next week without risking a visible line in your river. Here's how we help customers at Desert Hardwoods size their pour before they ever open a kit.

Four ways to calculate your resin

Pick the method that fits your project and how much math you want to do. All four should land within a few percent of each other.

Option 1: The volume formula (most accurate)

Multiply the river's length, average width and depth in inches to get cubic inches. Then divide by 231, because one US gallon holds 231 cubic inches.

Gallons = Length (in.) × Average width (in.) × Depth (in.) ÷ 231

Working in metric? Multiply centimeters to get cubic centimeters, then divide by 1,000 for liters.

One note: depth means the depth of the resin, not the mold. If your slabs are 2 in. thick and you'll flatten them to 1.75 in., use 1.75 in. plus a little extra for the top to be planed flush.

Option 2: The square-foot shortcut (quickest)

Every square foot of river surface takes about 0.62 gallons for each inch of depth. Find the river's surface area in square feet, then multiply.

Gallons = River area (sq ft) × Depth (in.) × 0.62

Example: a river 96 in. long and 10 in. wide on average is 960 sq in, or 6.7 sq ft. At 2 in. deep, that's 6.7 x 2 x 0.62 = 8.3 gallons.

Option 3: Trace and count (best for wild, irregular edges)

When the river swings wide, narrows to nothing, or has big bark pockets, averaging widths gets shaky. Tracing gives you the true shape.

1.      Lay butcher paper or cardboard over the gap between your slabs and trace both edges.

2.      Draw a grid of 2 in. squares over the tracing. Each square is 4 sq in.

3.      Count the squares inside the river. Count partial squares as half.

4.      Multiply the count by 4 to get square inches, multiply by depth, and divide by 231 for gallons.

Option 4: An online resin calculator (easiest)

Most epoxy brands offer a free river table calculator on their website. Enter length, average width and depth, and it gives you the volume. They use the same math as Option 1, so measure carefully, and add your own 10 to 15% buffer if the calculator doesn't.

Buying by weight instead of volume?

Some resins are sold in pounds or kilos. Most epoxies weigh roughly 9 to 9.5 lb per gallon, but density varies by brand. Check the technical data sheet for your product, then multiply your gallons by that number.

Measuring a live-edge river

A live edge never runs straight, so the width is the tricky part. Take an average instead of guessing.

1.      Set your slabs in the mold exactly where they'll be poured.

2.      Measure the gap between the edges every 6 in. down the full length.

3.      Add all the measurements and divide by how many you took. That's your average width.

4.      Check for bark pockets, cracks and voids that dip below the river. Fill those with resin too, so add a rough estimate for them.

For a 72 in. table, that's 12 or 13 measurements. It takes a few minutes and is far more accurate than measuring the widest and narrowest points.

Common table sizes, worked out

Here's what the formula gives for three typical builds. The last column adds a 15% buffer, which is what we'd actually buy.

Table	Length (in.)	Avg. river width (in.)	Depth (in.)	Cubic inches	Gallons (exact)	Gallons to buy (+15%)
Coffee table	48	6	1.5	432	1.9	2.25
Desk	60	8	1.5	720	3.1	3.75
8 ft dining table	96	10	2	1,920	8.3	10

Notice how fast it climbs. Adding just 2 in. of river width to the dining table adds almost 2 more gallons.

Once you have your number, you can pick up Wisebond epoxy and Black Diamond pigments from us along with your wood, so everything arrives together.

Why you need more than the formula says

The formula gives you the river itself. Real pours always use more, which is why we add 10 to 15%.

•       Wood soak. Dry wood drinks resin along the edges and end grain, especially on the first pour.

•       Leaks. Even a well-sealed mold can seep at the corners.

•       Leftovers. Some resin always stays in the mixing bucket and on the stir stick.

•       Voids and bark pockets. Hidden cavities fill up before the river level rises.

Also plan for these separate coats, which the formula doesn't include:

•       Seal coat. A thin coat brushed on the slab edges before the main pour stops air bubbles from rising out of the wood. A quart is usually plenty.

•       Flood coat (optional). If you top the whole table with a glossy resin coat instead of oil or finish, 1 gallon covers about 12 sq ft at 1/8 in. thick. An 8 ft dining table at 96 x 40 in. is about 27 sq ft, so plan on roughly 2 gallons of tabletop epoxy.

Tips for olive wood and desert pours

•       Use deep pour epoxy for the river. Tabletop epoxy is made for thin coats. Poured 2 in. deep, it can overheat, crack or yellow. Check the label for the maximum pour depth and split the pour into layers if your river is deeper.

•       Make sure the wood is dry. Moisture trapped in the slab causes bubbles and can weaken the bond. Olive is dense, so give it time.

•       Watch the heat. Epoxy cures faster as temperature rises. In a Phoenix garage in summer, that can mean a shorter working time and a hotter cure. Pour in the cooler months, or early in the morning in a climate-controlled space, and follow the manufacturer's temperature range.

•       Mix one batch if you can. Mixing all your resin at once avoids color differences between batches. For big pours, mix in several buckets back to back with the same measured amount of pigment in each.

Everything you need for your river table

The river gets the attention, but the wood makes the table. At Desert Hardwoods, we mill live-edge olive wood right here in Arizona, and every listing shows the exact piece you'll get. We also carry the resin and color to finish the job.

•       Live edge olive wood slabs: dried slabs ready for your mold.

•       Olive wood for river tables: slabs and pieces picked for resin work.

•       Pre-cut olive wood kits: pieces laid out for a specific table size, set close together to keep your resin cost down. Building a dining table? See our olive wood for dining tables.

•       Wisebond epoxy: resin for your pour.

•       Black Diamond pigments: color for your river.

Shipping is free with 3-day UPS ground, and you're welcome to see slabs in person by appointment. Have questions about sizing your pour? Reach out and we'll help you work out the numbers.