Craft Calculators

Resin & epoxyNo. 101

Updated October 2026

Epoxy Resin Calculator

Find how much resin and hardener to mix for a table top, river table, coasters or a mold. Works in inches or centimeters and splits deep pours into layers.

Project
Examples:
Measurements
in
in
in
pcs

Fractions work too: type 1/8 or 1 1/2.

Epoxy

Typical: 2:1 by volume, up to 2 in (5 cm) per pour. Check your label.

Mix ratio (A : B)
in
Extra
10%
Advanced
g/ml

Used for weights. Most epoxies are 1.05 to 1.20.

How much epoxy do I need?

Epoxy fills a volume, so the math is length times width times depth. For a round piece, use the area of the circle instead of length times width. Convert the volume to the units on your bottles and add a margin for the film left in the mixing cup, drips over the edges and small measuring errors.

Volume (cubic inches) = length × width × depth Fluid ounces = cubic inches ÷ 1.805 Gallons = cubic inches ÷ 231 Milliliters = cubic centimeters Round piece = 3.1416 × (diameter ÷ 2)² × depth

Example. A 24 × 18 in tray top poured 1/8 in deep holds 54 cubic inches, which is 29.9 fl oz. With 10% extra you need about 32.9 fl oz of mixed epoxy, so 16.5 fl oz of resin and 16.5 fl oz of hardener at a 1:1 ratio.

Epoxy coverage per gallon

Use this chart to check a quote or a kit size at a glance. Figures assume a flat, sealed surface with no runoff.

ThicknessSq ft per gallonThickness (mm)m² per liter
1/16 in25.71.60.63
1/8 in12.83.20.31
1/4 in6.46.40.16
1/2 in3.212.70.08
1 in1.625.40.04
2 in0.850.80.02

Mix ratios: by volume or by weight

Epoxy comes in two parts: Part A is the resin and Part B is the hardener. The ratio on the label, such as 1:1 or 2:1, tells you how much of each to combine. Coating and art resins usually mix 1:1, and many deep pour resins mix 2:1 or 3:1, but this varies by brand.

Check whether your label gives the ratio by volume or by weight. The two parts have different densities, so the numbers are not interchangeable. If your label gives a weight ratio, choose Ratio by weight and the calculator splits the estimated weight of the mix instead of its volume.

Measure each part in its own graduated cup, then combine them and stir slowly for the time on the label, scraping the sides and bottom of the cup.

How thick can you pour epoxy?

Epoxy cures through a chemical reaction that gives off heat. A thicker pour traps more of that heat, so every product has a maximum depth per pour. Going past it can crack the casting, trap bubbles, turn it yellow or make it cure too fast.

  • Coating or table-top epoxy: thin flood coats, often around 1/8 in (3 mm) at a time.
  • Art and casting resin: coasters, jewelry and small molds, often up to about 1/2 in (12 mm).
  • Deep pour epoxy: river tables and thick castings, often 1 to 2 in (25 to 50 mm) per layer, sometimes more.

These are typical ranges. The label on your product sets the real limit, and a warm room lowers it. Enter the label's number as the maximum depth per pour and the calculator splits the job into layers.

Measuring an irregular mold

Silicone molds, bowls and live-edge gaps are hard to measure with a ruler. Use water instead:

  1. Fill the mold with water up to the height you plan to pour.
  2. Pour the water into a measuring cup and note the amount.
  3. Choose Measured volume above and enter that number.
  4. Dry the mold completely before pouring. Water interferes with the cure.

Questions

How do I calculate how much epoxy I need?

Multiply length by width by depth to get the volume of the pour. In inches, divide the cubic inches by 1.805 for fluid ounces or by 231 for gallons. In centimeters, cubic centimeters equal milliliters. Then add about 10% for the film left in the mixing cup and for drips.

How much epoxy do I need for a river table?

Multiply the length of the river by its average width and by the pour depth. Measure the width in several places, because live edges vary. Deep pour epoxy usually goes in layers of 1 to 2 inches, and you will also need a little extra to seal the wood edges before the main pour.

How many square feet does a gallon of epoxy cover?

At 1/8 inch thick, one gallon covers about 12.8 square feet. At 1/16 inch it covers about 25.7 square feet, and at 1/4 inch about 6.4 square feet. Porous or uneven surfaces take more.

Can I measure epoxy by weight instead of volume?

Only with the weight ratio from your product's label. Resin and hardener have different densities, so a 1:1 ratio by volume is usually not 1:1 by weight. Mixing by weight with a volume ratio gives the wrong mix and can leave a soft or sticky cure.

Why does epoxy need to be poured in layers?

Epoxy gives off heat as it cures, and a thick pour traps that heat. Too much heat can cause cracking, bubbles, yellowing or a flash cure. Each product lists a maximum pour depth on its label. Stay under it and pour the next layer once the previous one has set.

How do I find the volume of an irregular mold?

Fill the mold with water to the height you plan to pour, pour the water into a measuring cup, and enter that number with the Measured volume option. Dry the mold completely before pouring epoxy, because water interferes with the cure.

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