π« Epoxy Resin Calculator
Total gallons plus the resin and hardener parts for your pour.
Total Mixed Epoxy (5% waste included)
For planning only. Work in a ventilated area, wear a respirator and gloves, and follow your epoxy brand\'s pour-depth and ratio instructions exactly.
How to Use This Calculator
Enter the length, width, and depth of your pour in inches, then pick your epoxy\'s mix ratio. For a river table, measure the river channel itself, not the whole table. For a coating, enter the project area and the coating depth (a typical flood coat is about 1/8 inch, or 0.125). The calculator adds 5 percent for waste and splits the total into resin and hardener.
Measure the pour area. For a river table, measure just the void between the wood slabs. For a coating, measure the full surface.
Enter the depth in inches. Use 0.125 for a standard flood coat, 0.0625 for a seal coat, or the full river depth for a deep pour.
Select your mix ratio from the product label: 1:1 for most coatings, 2:1 for most deep-pour formulas. Measure by volume, not weight, unless the label says otherwise.
Compare the total gallons against kit sizes. Epoxy kits are sold by total mixed volume (a "3-gallon kit" makes 3 gallons of mixed epoxy), so buy the next kit size up.
The Epoxy Volume Formula
One US gallon is exactly 231 cubic inches, which makes the conversion clean. The 5 percent waste factor covers the epoxy that clings to mixing cups, stir sticks, and the corners of your mold. It is deliberately small because epoxy is expensive: measure your mold carefully and level it, since an unlevel mold pours extra depth on the low side.
The mix ratio is chemistry, not a suggestion. Epoxy cures by a chemical reaction between resin and hardener in a fixed proportion. Too much hardener leaves unreacted chemicals that keep the surface soft and tacky; too much resin leaves soft spots. Measure both parts in graduated mixing cups and mix for the full time the label specifies, scraping the sides and bottom.
Worked Example
A river table channel 36 inches long, 8 inches wide, and 1.75 inches deep with 2:1 deep-pour epoxy. Volume = 36 x 8 x 1.75 = 504 cubic inches. Gallons = 504 / 231 = 2.18. With 5 percent waste: 2.29 gallons. Resin = 2.29 x 2/3 = 1.53 gallons. Hardener = 2.29 / 3 = 0.76 gallons. Buy a 3-gallon kit, since a 2-gallon kit falls short.
Coating example: a 24x18 inch serving tray with a 1/8-inch flood coat. Volume = 24 x 18 x 0.125 = 54 cubic inches = 0.234 gallons. With waste: 0.245 gallons, about 31 fluid ounces. A quart kit (32 oz) just covers it with 1:1 epoxy: 15.5 oz resin and 15.5 oz hardener.
Tips for a Clear Pour
Temperature controls everything. Keep the room, the wood, and the epoxy itself between 70 and 75Β°F. Cold epoxy is thick, traps bubbles, and cures slowly; a warm water bath for the resin bottles (before mixing) thins them for easier pouring. Warm the shop, not the mixed epoxy: heating mixed epoxy accelerates the exothermic reaction and shortens your working time.
Seal porous wood first with a thin brushed seal coat and let it get tacky before the main pour. This stops the endless stream of bubbles that raw wood releases into the epoxy. And always do a test pour on scrap with your exact ratio, depth, and room temperature. A small test costs almost nothing and catches problems (bad ratio, cold room, moisture in the wood) before they ruin the real project.
Frequently Asked Questions
What is the difference between 1:1 and 2:1 epoxy?
The ratio is resin to hardener by volume. 1:1 epoxy uses equal parts and is common for thin coatings and art projects. 2:1 epoxy uses two parts resin to one part hardener and is typical for deep-pour and river-table formulas that cure in thick layers. Always follow your specific product's ratio: the wrong ratio will not cure properly.
How deep can I pour epoxy in one layer?
Standard tabletop epoxy is poured at 1/8 inch or less per layer. Deep-pour formulas are rated for 2 to 4 inches per pour, depending on the brand. Pouring thicker than rated traps heat from the exothermic reaction, which can yellow, crack, or even smoke the epoxy. When in doubt, pour thinner and add layers.
How do I get rid of bubbles in epoxy?
Mix slowly to avoid whipping air in, then pop surface bubbles with a quick pass of a heat gun or torch held 6 to 8 inches away and kept moving. A second pass 10 to 15 minutes later catches bubbles that rise late. Sealing porous wood with a thin seal coat first stops most bubbles at the source.
How long does epoxy take to cure?
Most tabletop epoxies are tack-free in 8 to 24 hours and fully cured in 72 hours. Deep-pour formulas take longer: 48 to 72 hours to demold and up to 7 days for full cure. Temperature matters a lot; cold shops slow curing dramatically, so keep the work area above 70Β°F if you can.
Can I use epoxy resin outdoors?
Most epoxies yellow and degrade under UV light, so they need a UV-stable topcoat (like spar urethane or marine varnish) for outdoor or sun-exposed use. There are UV-resistant formulas, but even those benefit from a protective topcoat. Never leave a raw epoxy river table in direct sun and expect it to stay clear.