The math is just area × depth
Multiply the surface area by the pour depth, and convert: in inches, cubic inches × 0.554 = US fluid ounces (a gallon is 231 in³); in centimeters, cubic centimeters are milliliters. The famous rule of thumb follows directly: one gallon covers about 12.8 sq ft at a 1/8" flood coat. Everything else — seal coats, deep pours, embedded objects — is adjusting that one multiplication.
Part A and Part B: measure by volume, carefully
Epoxy kits cure by exact chemistry, and "roughly half-and-half" is how sticky tables happen. For a 1:1 kit, each part is half the total; for 2:1, Part A is two thirds. The calculator does the split for your pour, but two cautions: some brands specify ratios by weight, which differs from volume because the parts have different densities — follow your label — and always mix a touch longer than feels necessary, scraping the cup walls.
Why the 10% margin isn't optional
Mixing cups hold back a few percent, porous wood drinks a seal coat, edges drip, and stopping mid-pour to mix more leaves a visible line. Buy to the margin figure, and for first-time deep pours check your resin's maximum pour depth — thick pours of tabletop resin overheat, yellow and crack.
FAQ
Tabletop amount?
24×48" at 1/8" ≈ 80 fl oz mixed; add 10%.
The formula?
Area × depth; ×0.554 for fl oz from cubic inches, cm³ = ml.
Gallon coverage?
About 12.8 sq ft at 1/8".
1:1 vs 2:1?
Half-and-half vs two-thirds/one-third by volume — unless your brand says by weight.
Why buy extra?
Mixing loss, edges and seal coats — running out mid-pour ruins the finish.