Epoxy calculator: how much epoxy resin do you need?

The calculator starts with a 48 × 24 in (4 × 2 ft) top at a 1/8 in flood coat — the thick, self-levelling coat most tabletop epoxies are made for.

The epoxy volume formula

Every epoxy estimate comes down to one idea: the volume of the space you’re filling or the layer you’re spreading. For a rectangle that’s length × width × depth; for a circle, π × radius² × depth. Work in inches and you get cubic inches; work in centimeters and you get milliliters (1 cm³ = 1 ml). Then convert to whatever unit your kit is sold in.

rectangle: L × W × D     circle: π × (diameter ÷ 2)² × D
1 US gallon = 231 cu in = 128 fl oz = 3.785 L
1 fl oz = 1.805 cu in = 29.57 ml
1 L = 1,000 cm³

Example: a 48 × 24 in tabletop with a 1/8 in flood coat is 48 × 24 × 0.125 = 144 cubic inches. Divided by 231 (a US gallon is exactly 231 cubic inches) that’s 0.62 gallons, or about 80 fl oz. With 10% extra you’d mix about 0.69 gallons — 88 fl oz — so a 1-gallon kit covers it with a little to spare. In metric, a 120 × 60 cm top at 3 mm is 120 × 60 × 0.3 = 2,160 ml, or about 2.38 liters with 10% extra.

Coverage per gallon

For coatings, it’s often easier to think in coverage. At a given thickness, a gallon covers a fixed area: about 12.8 sq ft at 1/8 in, 25.7 sq ft at 1/16 in, and 6.4 sq ft at 1/4 in — the same figures TotalBoat prints for its 1-gallon TableTop kit. ArtResin’s rule of thumb is about 4 oz per square foot — by the arithmetic a coat of roughly 1/20 in, well under the 10 fl oz a true 1/8 in coat takes. In metric, one liter covers 0.33 m² at 3 mm. The calculator shows the coverage for whatever depth you enter; the epoxy coverage chart lists every common thickness.

Which epoxy for the depth

Depth decides the product more than volume does. Coats up to about 1/4 in are tabletop or art-resin territory (TotalBoat’s TableTop, for example, is rated for up to 1/4 in per coat). From about 1/4 in to 1 in, a casting or medium-pour resin fits — thin enough to fill a mold or a knot hole, slow enough not to overheat at that depth. Past about 1 in you need a slow deep-pour epoxy such as MAS Deep Pour X, made for 2–3 in per pour — and past its rated depth, separate layers, each poured once the one below has firmed up. Deep-pour resins also have a minimum depth, and can stay soft if poured too thin. The recommendation under the result follows the depth you enter; the label on your kit has the final say.

Filling cracks, knot holes or small voids in wood rather than a rectangle? The void, crack and knot fill calculator adds up each void with a shape factor for its taper, and allows for resin soaking into the wood and for the smallest batch you can mix.

Waste, weight and mix ratio

• Waste: 10% suits most pours. Use 15% or more for flood coats that drip off edges, for porous wood, or for many small batches.
• Weight: mixed epoxy is typically 1.05–1.2 g/ml, which is roughly 9–10 lb per gallon. The calculator uses 1.1 g/ml — see how much a gallon of epoxy weighs for the range.
• Mix ratio: the Part A and Part B rows at the end of the result are mixing amounts, not a shopping list — every kit already has both bottles. Pick your kit’s ratio under More options, by volume (1:1, 2:1, 3:1) or by weight (100:44 and similar), and the calculator gives each part in cups and on a scale. Resin and hardener rarely weigh the same, so a 1:1 kit isn’t 1:1 on a scale; if your data sheet lists each part’s specific gravity (weight per ml), enter it for exact weights. See 1:1 epoxy by weight in grams, or the mix ratio calculator for any ratio.