Epoxy Resin Calculator

Epoxy Resin Calculator

Find out exactly how much epoxy you need. Enter your project size and mix ratio to get total volume, Part A and Part B instantly.

Resin Volume Calculator

Project Shape
Units
in
in
in
in

From your product label. Leave blank to use the generic 2 inch (5 cm) rule.

%

Extra to cover cup residue and spillage. 5-10% is typical.

Measure by

Use Weight if your product label gives the ratio by weight. Resin and hardener have different densities, so the split changes.

Your Results

Total Epoxy Needed

132fl oz

Part A (Resin)

65.8fl oz

Part B (Hardener)

65.8fl oz

Equivalent by weight: A 75.5 / B 65.2 oz

Cavity volume: 216 in³

Recommended for this pour

Deep Pour Casting Resin (2:1)

Low-exotherm formula designed for 2-4 inch single pours. The right choice for river tables and thick castings.

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Essential mixing tools

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How Much Epoxy Do I Need? How to Calculate Resin Volume

Working out epoxy volume comes down to three steps: measure the cavity, convert cubic measurements to liquid volume, then split that volume by your mix ratio. This calculator does all three, but here is the math so you can check it by hand.

  1. Step 1: Measure the cavity

    For a rectangular pour such as a river table channel, multiply Length x Width x Average Depth. For a round mold or coaster, use pi x (Diameter / 2)^2 x Depth. Measure the deepest and shallowest points and average them for an irregular channel.

  2. Step 2: Convert to liquid volume

    One cubic inch equals 0.554 US fluid ounces, and one cubic centimetre equals one millilitre. A 12 x 12 x 1 inch pour is 144 cubic inches, or roughly 80 fl oz of mixed epoxy.

  3. Step 3: Split by mix ratio

    For a 2:1 epoxy, divide the total by 3: two parts are resin (Part A) and one part is hardener (Part B). Always measure by volume unless your product specifies mixing by weight.

  4. Step 4: Add a waste allowance

    Resin clings to cups and stir sticks and you will always lose a little. Mixing 5-10% extra prevents running short mid-pour, which can leave visible seams.

Calculating resin for a river table

River tables are the most common deep pour project. Measure the length of the channel, then take the width at several points and average them since live-edge slabs are rarely straight. Depth is your slab thickness. Because river channels usually exceed 1.5 inches, use a deep pour epoxy and set this calculator to the 2:1 or 3:1 ratio your product specifies.

Epoxy Mix Ratios Explained: 1:1 vs 2:1 vs 3:1

The mix ratio is the volume of resin (Part A) to hardener (Part B). It is set by the chemistry of the product and is not adjustable. A wrong ratio leads to soft, sticky or cloudy epoxy.

1:1 Table top and coating epoxy

Equal parts resin and hardener. Fast-curing, thick and self-levelling. Ideal for bar tops, art, and coats up to about 1/8 inch per layer. Generates a lot of heat, so it is not suitable for deep casting.

2:1 Deep pour and casting epoxy

Two parts resin to one part hardener. Slower cure with a lower exotherm, allowing single pours of 2 to 4 inches. This is the standard for river tables and large castings.

3:1 and 4:1 Specialty and marine epoxies

Common in laminating, boat-building and some deep casting systems. These require precise measurement because a small error in the hardener has a big effect on the cure.

Frequently Asked Questions

How much epoxy do I need for a 12x12 inch surface?

For a 1/8 inch coating over 12 x 12 inches you need about 10 fl oz of mixed epoxy. At a 1 inch depth the same area needs roughly 80 fl oz (about 2.4 litres). Use the calculator above for your exact depth.

Does the calculator measure by volume or by weight?

Both. The default is by volume (fluid ounces or millilitres), which is how most consumer epoxies are labelled. Switch "Measure by" to Weight if your product gives the ratio by weight. Enter the specific gravity of each part from the technical data sheet and the tool converts the cavity volume into grams or ounces of resin and hardener.

What is the maximum depth for table top epoxy?

Most 1:1 coating epoxies are limited to 1/8 to 1/4 inch per pour. Anything over 2 inches in a single pour needs a dedicated deep pour epoxy formulated to release heat slowly.

Why do I need extra epoxy beyond the calculated amount?

Some epoxy is always left behind in mixing cups and on stir sticks, and wood absorbs a small amount. Adding 5-10% extra ensures you can complete the pour in one go.

Can I pour epoxy in layers instead of using deep pour resin?

Yes. Pour coating epoxy in layers within its maximum thickness and let each layer reach a tacky cure before adding the next. Deep pour epoxy is simpler for thick sections because it avoids layer lines.