How much epoxy resin you need
Epoxy is sold by volume, so the job is to work out the volume of the space you're filling. For a flat coat that's the surface area times the pour depth. For coasters it's the area of a circle times the depth, times the number of pieces. For a river table only the channel between the slabs gets filled, so you use the river's length times its average width, or a share of the whole table area if you've sketched it out that way. The calculator converts cubic inches to fluid ounces, adds a waste allowance, and splits the total by your kit's mix ratio.
The formula
circle volume = π × (diameter ÷ 2)² × depth × pieces
river volume = length × average river width × depth
fluid ounces = cubic inches ÷ 1.805
total to mix = fluid ounces × (1 + waste %)
part A = total × A ÷ (A + B), part B = total − part A
The 1.805 comes from the US gallon: 231 cubic inches divided by 128 fluid ounces. Mix ratios here are by volume, which is how most hobby kits are labeled. If your kit gives a ratio by weight, measure on a scale using the label's numbers, because resin and hardener rarely have the same density.
Example: a 48 × 24 inch table top
A single flood coat 1/8 inch deep on a 48 × 24 inch top, with a 1:1 resin, 10% extra, and a $100 one-gallon kit:
| Step | Result |
|---|---|
| Volume: 48 × 24 × 0.125 | 144 cu in |
| Fluid ounces: 144 ÷ 1.805 | 79.8 fl oz |
| With 10% waste | 87.8 fl oz (2,596 ml, 0.686 gal) |
| Part A / Part B at 1:1 | 43.9 fl oz each |
| Kits: 87.8 ÷ 128 | 1 kit, $100.00 |
Pour depth: coating resin vs deep-pour resin
Epoxy gives off heat as it cures, and a thick mass traps that heat. Too much in one pour can yellow, crack, ripple, trap bubbles or even smoke. Manufacturers design products around a maximum layer depth:
| Resin type | Typical mix | Max per layer |
|---|---|---|
| Tabletop / coating | 1:1 | About 1/8 in |
| Art resin | 1:1 | About 1/4 in |
| Deep pour / casting | 2:1 or 3:1 | 1–4 in, depending on product |
The "pours at label limits" line assumes 1/8 inch per tabletop coat and 2 inches per deep-pour layer. Your label wins, especially for deep-pour resins, where some allow only 1 inch and others 4 inches. Wait for each layer to cool and firm up as directed before pouring the next.
Tips for estimating accurately
- Measure a river channel in several places. Live edges wander. Measure the width every foot or so and average the numbers, and use the deepest point of the mold for depth.
- Seal the wood first. Bare wood absorbs resin and releases air bubbles. A thin seal coat, worked in with a brush or spreader, uses roughly a quarter of what a flood coat does.
- Raise waste for river tables. Bark pockets, cracks and a mold that may seep easily eat 15–20% extra. Running short partway through a deep pour is far worse than having leftover resin.
- Mix in batches you can pour in time. Working time drops as the batch gets bigger. Deep-pour resins give you longer, but check the label's maximum batch size too.
- Work at room temperature. Most resins want about 70–80°F for pouring and curing. Cold resin is thick and holds bubbles.
Frequently asked questions
How much epoxy do I need for a table top?
Multiply length by width by pour depth in inches to get cubic inches, then divide by 1.805 to get fluid ounces. A 48 by 24 inch top with a 1/8 inch flood coat is 144 cubic inches, about 80 fluid ounces, or roughly 88 ounces once you add 10% for drips and the film left in the cup.
How much area does a gallon of epoxy cover?
A gallon is 231 cubic inches. At 1/8 inch deep it covers about 1,848 square inches, or roughly 12.8 square feet. At 1/16 inch it covers about 25 square feet, and at 1/4 inch about 6.4 square feet.
How deep can I pour epoxy in one layer?
It depends on the product. Tabletop and coating resins are usually limited to about 1/8 inch per coat, art resins to about 1/4 inch, and deep-pour or casting resins to anywhere from 1 to 4 inches per layer. Pouring deeper than the label allows traps heat, which can cause yellowing, cracking, bubbles or smoking.
Is the 2:1 mix ratio by volume or by weight?
This calculator treats every ratio as a volume ratio, which is how most hobby kits are written. Part A and Part B often have different densities, so a 2:1 volume ratio is not 2:1 by weight. If your label gives a weight ratio, mix by weight on a scale using the numbers on the label.
How much extra epoxy should I mix?
Add 10% for flat coats and coasters to cover drips over the edge, resin left in the cup and uneven surfaces. For river tables with porous live edges, bark voids or a mold that may leak, 15 to 20% is safer. Wood soaks up resin, so seal the wood with a thin coat first.
Rates and figures last checked September 2026.
This calculator gives estimates for planning. Check current rates and product labels before you buy, list or file.