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Epoxy Resin Calculator

Estimate the epoxy for a tabletop coating, a round pour or a river table, split into resin and hardener by your mix ratio.

Level: Grades 6–8

  • Common Core standard 7.G.B.6Solve real-world and mathematical problems involving area, volume and surface area of two- and three-dimensional objects composed of triangles, quadrilaterals, polygons, cubes, and right prisms.
  • Common Core standard 8.G.C.9Know the formulas for the volumes of cones, cylinders, and spheres and use them to solve real-world and mathematical problems.
  • Common Core standard 6.RP.A.3Use ratio and rate reasoning to solve real-world and mathematical problems, e.g., by reasoning about tables of equivalent ratios, tape diagrams, double number line diagrams, or equations.
Printable worksheet

Epoxy Resin Calculator

Know the answer you need? Pick an input to work backward.

Inputs
Units
Project

A flood coat is often about 1/8 in (0.125). Deep pours need a resin made for them; check its maximum layer depth.

From the product label, by volume. 1:1 and 2:1 are common.

Coatings run off the edges and some mix stays in the cup. 10–15% is a common allowance.

Result

Mixed epoxy needed

29.26 fl oz

Mix about 29.3 fl oz of epoxy: 14.6 fl oz resin and 14.6 fl oz hardener.

Resin (part A)
14.63 fl oz
Hardener (part B)
14.63 fl oz
Total in liters
0.865 L
Total in US gallons
0.229 gal
Total in milliliters
865 mL

See the step-by-step solution ↓

Step-by-step solution

  1. Find the surface area: length times width

    24×16=384 in²

  2. Multiply the area by the depth to get the volume to fill

    384×0.125=48 in³

  3. Change to fluid ounces (1 fl oz = 1.8046875 in³) and add 10% extra for drips and the cup

    481.8046875×1.1=29.2571 fl oz

  4. Resin (part A) is 1 of every 2 parts of the mix

    29.2571×11+1=14.6286 fl oz

  5. Hardener (part B) = the rest of the mix

    29.2571×11+1=14.6286 fl oz

Test yourself

20 quick questions built from this calculator's formula: work out results, predict what happens when an input changes, and work backward from an answer. Every answer comes with the working.

What this calculator does

Find out how much epoxy to mix for your project, and how much of each part to pour. Epoxy comes as two parts, the resin and a hardener. They only cure (set hard) when mixed in the right amounts. Mix too little and a coating runs thin or a pour stops short. Mix too much and the extra hardens in the cup, which gets costly with art and table resins. The amount you need is the volume of the space you're filling. Then add a little for what clings to cups and drips off edges.

This calculator finds that volume from the size and depth of your piece. It works for a rectangular coating or pour, a round piece such as a tray or table top, or the gap of a river table. It changes the volume to fluid ounces, milliliters, liters and gallons, and adds your extra allowance. Then it splits the total into part A (resin) and part B (hardener), using the mix ratio on your product's label.

Where it's used

Why this math matters outside the classroom:

  • Tabletop coats. Woodworkers coating a 24 × 16 in board 0.125 in thick need 48 in³, or about 26.6 fl oz before waste.
  • Round trays. Crafters pouring a 12 in round tray 0.5 in deep fill π × 6² × 0.5 = 56.5 in³ of mold.
  • River tables. Furniture makers fill a 72 in gap averaging 3.5 in wide and 1.25 in deep with 315 in³, about 1.36 gallons.
  • Mix ratios. For a 2:1 resin, 30 fl oz of mix is 30 × 2 ÷ 3 = 20 fl oz of resin and 10 fl oz of hardener.
  • Unit conversion. Students convert cubic inches to fluid ounces using 231 in³ per gallon and 128 fl oz per gallon.

Grade level and standards: Grades 6–8; Common Core State Standards for Mathematics 7.G.B.6, 8.G.C.9, 6.RP.A.3. © Copyright 2010. National Governors Association Center for Best Practices and Council of Chief State School Officers. All rights reserved.

How to use it

  1. Choose US or metric units and the type of project.
  2. Enter the length and width, or the diameter, or the river gap's length and average width. Then enter the thickness or depth of the pour.
  3. Enter the mix ratio by volume from the product label, plus some extra for waste.
  4. Read the total to mix and the amounts of resin and hardener.

What the inputs mean

Width (for a river table, the average gap width)
River gaps are rarely straight. Measure the gap's width every few inches along its length and average the readings. Then use that average as the width.
Thickness or pour depth
Coating resins are usually poured in thin flood coats (one even layer over the whole surface) of around 1/8 in (3 mm). Deep-pour casting resins can go thicker in one layer, but each product has a maximum. Deeper pours are done in several layers, and you can run the calculator for each one.
Mix ratio: resin (part A)
Use the ratio by volume. Some products also give a ratio by weight. That one is different, because one part is heavier for its size (denser) than the other.
Extra for drips, mixing cups and edges
This covers what stays in the mixing cup, what runs off the edges of a coating and any leaks from a mold. Self-leveling coatings that you let drip over the edges need more.

Formula and method

volume = length × width × depth  (rectangle or river gap)
volume = π × (diameter ÷ 2)² × depth  (round)
US: fl oz = in³ ÷ 1.8046875;  metric: cm³ = mL
total = volume × (1 + waste ÷ 100)
resin = total × A ÷ (A + B);  hardener = total × B ÷ (A + B)

In the formulas, π (pi) is about 3.14159, in³ means cubic inches and fl oz means US fluid ounces. A US gallon is exactly 231 in³ and holds 128 fl oz. So one fluid ounce is 231 ÷ 128 = 1.8046875 in³. In metric, depths in millimeters are divided by 10 to work in centimeters. One cubic centimeter (cm³) is one milliliter.

Waste is your extra allowance in percent. A ratio of A:B means A parts resin to B parts hardener. So the resin share of the total is A ÷ (A + B).

Worked example

A 24 × 16 in tabletop given a 1/8 in (0.125 in) flood coat of a 1:1 epoxy, with 10% extra.

  1. Surface area: 24 × 16 = 384 in².
  2. Volume: 384 × 0.125 = 48 in³.
  3. In fluid ounces with 10% extra: 48 ÷ 1.8046875 × 1.1 = 29.2571 fl oz.
  4. Resin: 29.2571 × 1 ÷ 2 = 14.6286 fl oz; hardener the same.

Result: Mix about 29.3 fl oz (0.87 L): roughly 14.6 fl oz of resin and 14.6 fl oz of hardener.

Understanding the result

Kits are sold by total volume, so compare the mixed total with the kit size. Buying a little more than you need is safer than running short in the middle of a pour.

Is the total more than you can pour in the product's working time (how long it stays runny)? Then plan several smaller batches and mix each one separately.

Assumptions and limitations

  • The surface is flat and the coating or pour has an even thickness.
  • The mix ratio is by volume.
  • Mold sides and the edges of a river table do not soak up epoxy.
  • Porous wood soaks up epoxy. A thin seal coat first, or a larger allowance, makes up for it.
  • Irregular molds and live-edge gaps are approximated by an average width.
  • Kits sold by weight need the product's density (weight per volume) to convert. Check the label.

Frequently asked questions

How much epoxy covers a square foot?

At 1/8 in thick, a square foot (144 in²) takes 18 in³, which is about 10 fl oz, or roughly 0.3 L. Twice the thickness takes twice as much.

How do I measure a river table gap?

Measure the length of the gap and its width at several points. Average the widths and enter the average. For the volume, multiply by the depth of the slab, or the depth you plan to pour.

Can I measure the two parts by weight?

Only if the product gives a ratio by weight. Resin and hardener usually have different densities, so a 1:1 ratio by volume isn't 1:1 by weight. Follow the label exactly. A mix with the wrong ratio may never fully cure.

Why add extra epoxy?

Some mix always stays on the cup walls and stir stick. A flood coat runs over the edges, and molds can leak. An allowance of 10 to 15% means you won't come up short on the last section of the pour.

How this calculator is checked

Method: Prism and cylinder volumes; exact US conversions (231 in³ and 128 fl oz per gallon, 16.387064 mL per in³); proportional split by mix ratio. The calculation is covered by automated tests with known reference values and edge cases. Last updated 2026-10-18. Found a problem? Tell us.

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