Epoxy Resin Calculator: How Much Resin for a Pour

This calculator works out how much epoxy resin to mix for a flat pour or coating. Enter the length and width of the piece, the depth of resin, an allowance for drips and the edges, and the mixing ratio by volume from your resin label; you get the total resin in fluid ounces and millilitres and how much of part A and part B to measure.

Formula

Volume (in³) = length × width × depth × (1 + extra ÷ 100). Fluid ounces = in³ ÷ 1.8047 (one US fl oz is 1.8047 in³). Millilitres = in³ × 16.387. Part A = total × r ÷ (r + 1) and part B = total ÷ (r + 1), where the label ratio is r : 1 by volume.

• l, w: size of the surface in inches
• d: depth of resin; a thin flood coat is often about 1/8 in (0.125 in)
• r: the label’s mixing ratio by volume, for example 1 for 1:1 or 2 for 2:1

Worked Example

A 24 × 12 in board, 1/8 in deep, 10% extra, 1:1 resin.

1. Volume = 24 × 12 × 0.125 = 36 in³; with 10% extra 39.6 in³
2. Fluid ounces = 39.6 ÷ 1.8047 = 21.94 fl oz
3. Millilitres = 39.6 × 16.387 = 649 mL
4. Part A = 21.94 × 1 ÷ 2 = 10.97 fl oz and part B = 10.97 fl oz

How to read the result

Measure both parts in the same unit and in the way the label says (by volume or by weight). For deep pours, check the maximum depth per layer on the label and pour in layers if needed; the total volume stays the same. For a round piece, enter the area as length and 1 as width.

Limits and common mistakes

• If your label gives the ratio by weight, convert with the densities on the label; volume and weight ratios are not the same.
• Porous wood soaks up resin; seal it first or add more allowance.
• Follow the label’s ventilation and skin-protection instructions.

Frequently Asked Questions

How much resin for a 2 × 4 ft table top at 1/8 in?

24 × 48 × 0.125 = 144 in³, about 80 fl oz before any allowance.

How many cubic inches are in a fluid ounce?

1.8047 in³ (a US gallon is 231 in³ and holds 128 fl oz).

Is 1:1 by volume the same as 1:1 by weight?

Not exactly; part A and part B usually have different densities. Use the ratio type your label states.

How much extra should I mix?

About 10% for flat coats; more for edges that drip, open grain or a first seal coat.

in l | Length | in | 24 | 0 | 10000
in w | Width | in | 12 | 0 | 10000
in d | Resin depth | in | 0.125 | 0 | 24
in waste | Extra for drips and edges | % | 10 | 0 | 100
in r | Mix ratio A : B (by volume) | : 1 | 1 | 0.1 | 20
out floz | Mixed resin needed | fl oz | l * w * d * (1 + waste / 100) / 1.8046875 | 2
out ml | Mixed resin needed | mL | l * w * d * (1 + waste / 100) * 16.387064 | 0
out pa | Part A (resin) | fl oz | floz * r / (r + 1) | 2
out pb | Part B (hardener) | fl oz | floz / (r + 1) | 2