Epoxy Pour Calculator
Measure the channel, get ounces, liters, and the exact Part A / Part B split — with a warning when your pour is too deep for table-top resin.
Verified against independent hand calculation · sources cited below
87.8 US fl oz mixed
2.60 L · 0.69 gal · includes 10% waste
Measure out: Part A (resin) 58.5 oz (1730 ml) + Part B (hardener) 29.3 oz (865 ml)
Mix ratio must follow your product’s data sheet — 1:1 and 2:1 by volume cover most table-top and deep-pour epoxies, but a few brands specify by weight, which is not the same because resin and hardener densities differ. River-table channels aren’t perfect rectangles: live edges usually net out around the rectangle’s volume, and the waste allowance covers the rest.
The formula, shown
Volume = L × W × D, then in³ × 0.554 = US fl oz. Worked example: a 24″ × 4″ × 1.5″ channel is 144 in³ ≈ 79.8 oz; with 10% waste, mix ~88 oz. At a 2:1 ratio that’s 58.5 oz Part A + 29.3 oz Part B.
Pouring without regrets
- Seal first. A thin seal coat on the wood stops bubble streams from the grain and reduces how much the slab drinks.
- Respect max depth. The calculator warns past 2″ — but the real limit is your product’s data sheet, and ambient temperature moves it.
- Mix what the math says, not what feels safe: huge single batches of deep-pour can still overheat in the bucket. Two medium batches beat one giant one.
- Level the form — epoxy is a liquid level; a 1° tilt on a 48″ table is a 0.8″ wedge.
Frequently asked questions
How much epoxy do I need for a river table?
A typical river channel 48″ long × 5″ wide × 1.5″ deep is 360 in³ ≈ 200 fl oz ≈ 1.55 gallons before waste. Real channels aren’t rectangles — live edges give and take — but the rectangle plus a 10% allowance lands remarkably close in practice.
What’s the difference between table-top and deep-pour epoxy?
Cure heat. Epoxy cures exothermically, and thick masses trap the heat: table-top formulas are fast and limited to roughly 1/8–1/4″ per layer, while deep-pour (casting) formulas cure slow and cool, allowing 2–4″+ in one go. Pour a river with table-top resin and it can smoke, yellow, and crack.
Is the mix ratio by volume or by weight?
Check your label — it matters. Most hobby epoxies specify by volume (1:1 or 2:1 with measuring cups), but some specify by weight, and the two are not interchangeable because resin and hardener have different densities. Off-ratio epoxy stays sticky forever; there is no fixing it after the pour.
How much extra should I mix?
A 10% allowance covers cup residue, seepage into wood grain and cracks, and topping off shrinkage on most projects; go 15% for very porous slabs or complicated molds. Running out mid-pour creates a visible cure line — mixing slightly over is the cheap insurance.
Sources & further reading
- Volume conversions: 1 in³ = 0.554 US fl oz; 231 in³ = 1 US gal; 61.02 in³ = 1 L
- Maximum pour depth is product-specific — always confirm on your resin’s technical data sheet before a deep pour