Epoxy Calculator
Find how much epoxy resin to mix for a tabletop, a bar top, a countertop, an art piece, or a deep pour such as a river table. Enter the surface and the pour thickness to see the epoxy you need in fl oz, gallons, mL, or liters, and enter your kit size to see how many kits to buy.
Add more surfaces, or subtract areas that need no epoxy, such as a sink cutout.
- Choose US or Metric. You can still change the unit of any single field.
- Choose the Shape of the surface and enter its dimensions. They start in inches (centimeters in Metric). For a round table, choose Circle, and for an oval table, Oval.
- Use Add section to add more surfaces, such as the two legs of an L-shaped counter. To leave out a sink or cooktop cutout, add a section for it and set it to Subtract. Use Quantity for several of the same size, such as a set of coasters.
- Choose the Thickness. It starts at a flood coat, 1/8 in (3 mm). For a deep pour or a mold, choose Custom thickness and enter the depth to fill.
- Optionally, enter the Kit size to see how many kits to buy, and a price per kit, gallon, or liter to estimate the cost.
Dimension fields accept whole numbers, decimals, fractions, and mixed
numbers, such as 24, 23.5, 3/4, or
47 1/2.
How much epoxy you need
The calculator multiplies the area of the surface by the thickness of the pour, then adds the waste allowance:
Epoxy = area × thickness × (1 + waste % ÷ 100)
Kits = epoxy ÷ kit size, rounded up
Convert every measurement to the same unit first. With inches, the area times the thickness gives cubic inches. A US gallon is 231 in³ and holds 128 fl oz, so divide cubic inches by 231 for gallons, or by 1.805 for fluid ounces. With centimeters, cm² × cm gives mL, and 1,000 mL is 1 liter.
With several sections, the calculator adds the sections set to Add and subtracts those set to Subtract. The area of each shape is calculated as follows:
| Shape | Area |
|---|---|
| Rectangle | length × width |
| Circle | π × diameter² ÷ 4 (or π × radius²) |
| Oval | π × length × width ÷ 4 |
| Triangle (base and height) | base × height ÷ 2 |
| Triangle (three sides) | Heron's formula: √(s(s − a)(s − b)(s − c)), where s = (a + b + c) ÷ 2 |
| Trapezoid | (parallel side A + parallel side B) ÷ 2 × height |
| Ring | π × (outer diameter² − inner diameter²) ÷ 4 |
| Rectangular border | outer length × outer width − (outer length − 2 × border width) × (outer width − 2 × border width) |
| Known area | the area you enter |
Seal coat, flood coat, and deep pour
The thickness is the depth of epoxy you pour over the whole surface. The calculator uses one thickness for every section.
| Coat | US | Metric |
|---|---|---|
| Seal coat | 1/16 in | 1.6 mm |
| Flood coat | 1/8 in | 3 mm |
- Flood coat. Most tabletop and bar top epoxies self-level to about 1/8 in per coat. Alumilite's Resin Coating 101 recommends 1/8 in for flood coating, and ArtResin gives 1/8 in (3 mm) as the ideal thickness for each pour. A 1 gal kit at 1/8 in covers 231 ÷ 0.125 = 1,848 in², about 12.8 ft², which matches the coverage TotalBoat lists for its TableTop Epoxy.
- Seal coat. A thin first coat on wood and other porous surfaces keeps air bubbles from rising into the flood coat. Guides give different amounts, from 1/64 in to 1/16 in. The calculator uses the largest, Alumilite's 1/16 in, so the seal coat doesn't run short. TotalBoat notes that a seal coat is only needed on wood or other porous materials.
- Deep pour. River tables, live edge slabs, and castings are filled to a depth that depends on the piece, so there is no preset. Choose Custom thickness and enter the depth.
Some products cover more than these values. For example, Stone Coat Countertops estimates 20 ft² per gallon, and ArtResin lists up to 32 ft² for a 1 gal kit. If your product lists its coverage, compare it with the result, or enter the thickness it implies.
For a river table, the river and the flood coat over the whole top usually use different products. Calculate the river with its depth as a custom thickness, then calculate the flood coat over the whole top separately.
Extra epoxy for waste and drips
Some epoxy always stays on the stir stick and in the mixing cup. TotalBoat suggests adding 5% to 10% for this, and Promise Epoxy says its estimates can vary by about 10%. The waste allowance starts at 10%.
If you let the epoxy run over the edges instead of building a dam, you'll need much more. UltraClear says you can lose about 30% of the material coating the edges and sides, so raise the waste allowance to about 30%. Running short in the middle of a pour is hard to fix, which is why Promise Epoxy suggests having about 20% more than you need.
Epoxy kit sizes
Epoxy is sold in kits of resin and hardener, and the kit size is the combined volume of both parts. A 1 gal kit, for example, holds 1/2 gal of resin and 1/2 gal of hardener. Enter that combined volume as the Kit size.
Common tabletop kit sizes include 16 fl oz, 32 fl oz, 1 gal, and 2 gal. Sizes vary by brand, so the calculator doesn't list them. The result is a volume, so you can also combine sizes, such as a 1 gal kit and a 32 fl oz kit.
Some kits sold in metric countries are labeled by weight, such as 1 kg or 5 kg. Enter the volume from the product details if it's listed. If not, Easy Composites suggests treating 1 kg of its epoxy as about 1 L.
Examples
A bar top
A bar top 36 in × 96 in is 3,456 in², or 24 ft². A flood coat of 1/8 in takes 3,456 × 1/8 = 432 in³, and 475.2 in³ with 10% added. That's 475.2 ÷ 231 = 2.06 gallons, so buy three 1 gal kits.
A countertop with a sink cutout
A counter 25 in × 120 in with a 33 in × 22 in sink cutout is 3,000 − 726 = 2,274 in². A flood coat with 10% added takes 312.675 in³, or 1.35 gallons, so one 2 gal kit is enough.
A river table
A river 6 in wide, 72 in long, and 2 in deep takes 6 × 72 × 2 = 864 in³, and 950.4 in³ with 10% added. That's 4.11 gallons of deep pour epoxy, or three 1.5 gal kits.
Metric dimensions
A table 120 cm × 60 cm is 0.72 m². A 3 mm flood coat takes 0.72 × 3 = 2.16 L, and 2.38 L with 10% added, so three 1 L kits.
FAQ
About 87.77 fl oz (0.69 gal) for a 1/8 in flood coat with 10% extra. The top is 1,152 in², so a flood coat takes 144 in³, or 158.4 in³ with extra. One 1 gal kit or three 32 fl oz kits are enough.
About 12.8 ft² at 1/8 in thick. A gallon is 231 in³, and 231 ÷ 0.125 = 1,848 in², or 12.83 ft². A seal coat of 1/16 in covers about twice as much. Check the coverage your product lists.
Divide cubic inches by 1.805 for US fluid ounces, or by 231 for US gallons. There are 128 fl oz in a gallon, so 231 ÷ 128 = 1.8046875 in³ per fluid ounce.
Multiply the river's length, average width, and depth. A river 72 in long, 6 in wide, and 2 in deep takes 864 in³, or about 4.11 gal with 10% extra. Enter the depth as a custom thickness, and calculate the flood coat over the whole top separately.
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