Quick answer: One gallon of epoxy covers about 12 sq ft at 1/8-inch thick. Volume = length × width × depth (in inches) ÷ 231 for gallons. Deep pours must be done in limited lifts to control heat.
Calculate exact volume, weight, and cost for river tables, molds, and deep pours.
Epoxy is sold by volume, not weight, so the math starts with length × width × depth to get a raw volume, then converted into gallons or liters (231 cubic inches per gallon). The number most people get wrong is depth: deep-pour epoxy can only safely cure in lifts of about 2 inches at a time, because thicker pours trap exothermic heat and risk cracking, yellowing, or even boiling the resin in the mold. If your project is deeper than your epoxy's rated lift thickness, you need to plan for multiple staged pours, letting each layer skin over (usually 24 hours) before adding the next — which is exactly what the "pours required" result above tells you.
Table-top/coating epoxy self-levels in thin layers (up to 1/8") and is used for sealing bar tops and countertops. Deep-pour epoxy is engineered to cure clear in 1–2 inch lifts without overheating, making it the standard choice for river tables. Casting resin cures slower still and is used for molds, jewelry, and small objects where crystal clarity matters more than working time. Using a table-top epoxy for a deep river table pour is the most common beginner mistake — it will overheat, cloud, and often crack.
Epoxy resin and hardener are mixed by a fixed ratio (commonly 1:1 or 2:1 by volume) that must be measured precisely — unlike paint, "eyeballing" epoxy ratios leads to a tacky, never-curing surface. Always measure resin and hardener in separate cups by volume (not weight, unless your manufacturer specifies a weight ratio) and mix for the full time stated on the product, typically 3–5 minutes, scraping the sides and bottom of the cup.
Most deep-pour epoxies are rated for a maximum lift of about 2 inches per pour. Pouring thicker than that in one go traps too much exothermic heat, which can cause cracking, yellowing, or even cause the resin to boil.
If your total depth is greater than your epoxy's rated max lift thickness, you need to pour in stages, letting each layer cure (usually 24 hours) before adding the next. This calculator divides your total depth by the lift thickness to tell you how many pours to plan for.
One gallon of mixed epoxy resin covers about 144 square inches at 1 inch deep (231 cubic inches per gallon). For a river table or deep mold, always calculate by volume rather than surface area, since pour depth varies.
Table-top epoxy is formulated for thin self-leveling coats and will overheat if poured deep. Deep-pour epoxy uses a slower-curing chemistry specifically designed to release heat gradually in 1–2 inch lifts, which is essential for river tables and other thick castings.
An incorrect mix ratio is the most common cause. Even small measuring errors prevent a full cure. Cold room temperature (below 65°F) can also slow curing dramatically — most epoxies need 70–75°F to cure on schedule.
Planning a woodworking or maker project? These tools pair well with the epoxy calculator:
Volume ÷ 231 gives US gallons. Mixed epoxy weighs about 9.5 lb per gallon. Deep pours must be split into lifts.
| Project | Size (L x W x D, in) | Cubic inches | Gallons | Weight | Lifts @ 2 in max |
|---|---|---|---|---|---|
| Small cheese board | 24 x 12 x 0.25 | 72 | 0.31 | 3.0 lb | 1 |
| Serving tray | 36 x 18 x 0.25 | 162 | 0.70 | 6.7 lb | 1 |
| Table top coat | 48 x 24 x 0.125 | 144 | 0.62 | 5.9 lb | 1 |
| Dining top coat | 60 x 30 x 0.125 | 225 | 0.97 | 9.3 lb | 1 |
| Small river pour | 36 x 6 x 1.5 | 324 | 1.40 | 13.3 lb | 1 |
| River table channel | 72 x 8 x 1.5 | 864 | 3.74 | 35.5 lb | 1 |
| Large river channel | 96 x 10 x 2 | 1,920 | 8.31 | 79.0 lb | 1 |
| Deep mould | 24 x 24 x 2 | 1,152 | 4.99 | 47.4 lb | 1 |
Maximum single-lift depth is product-specific: tabletop epoxy is often 1/8 in, deep-pour 2 in or more. Exceeding it causes the pour to overheat, yellow or crack. Always check the data sheet.
Every constant this calculator uses and where it comes from, so you can check it rather than take our word for it.
Local codes amend the model IRC and adopt different cycles — your building department governs. Manufacturers revise yields; where your product's data sheet disagrees with a default here, use the product's number. See our full methodology.