Epoxy and resin pour calculator

Shape: rectangle, round, river table (enter the river’s width at equal intervals along its length — the area uses the trapezoid rule), or Trace a photo: load a photo taken straight down, click both ends of something of known length to set the scale, then click around the pour area (area by the shoelace formula).

Embedded objects: slabs, rocks, or inserts that sit in the pour are subtracted (length × width × the depth they occupy).

Volume: area × depth − objects, plus a waste allowance for mixing cups, drips, and seepage into wood (10–15 % is typical; more for open-grain or unsealed live edges).

Mix: by volume, part A = V·a/(a+b). By weight, the volumes follow from the densities so that the masses keep the stated ratio. Mix by whichever basis your product specifies.

Layers: the depth is split into the fewest pours that stay within the product’s maximum pour depth; let each layer gel before the next.

Cure: as a rule of thumb, every 10 °C below about 24 °C roughly doubles cure time; deep pours in a warm room risk overheating (exotherm), cracking, and yellowing.

Colourant: a percentage of the total mixed weight — pigment pastes about 1–6 %, mica powders about 1–3 %, alcohol inks under 1 %. Too much colourant can stop a cure.