How Much Epoxy Do I Need? (5-Step Guide)

Last Updated On November 19, 2021

How Much Epoxy Do I Need? (5-Step Guide)

How much epoxy do you need? It depends on the project. Epoxy comes in many different forms and is used for many different projects, so understanding how much epoxy you need for the specific job helps avoid hiccups along the way. We’ve got all of your epoxy needs covered. Check out our take on epoxy:

What You Need To Know About How Much Epoxy Do I Need

Mix ratio

Most DIY epoxy projects come with a quick and easy 1:1 ratio formula, but industrial epoxy resins typically require a more offset ratio from part A to part B. For example, if you’re repairing fiberglass, the ratio will be something like 25:1 or 50:1 part ‘A’ to part ‘B’, so you’ll have to use a scale if you want the resin to cure at its maximum strength.

Desired thickness

Since epoxies are self-leveling, it’s important to carefully frame out where you want your epoxy to fall if you’re not using a mold.

Your desired thickness will determine how much the result weighs, and how strong it is. If you’re using fiberglass/carbon on your project, you need to determine what thickness of the fabric you want to use. Lighter fabrics require only a thin layer of resin, whereas thicker fabrics/porous surfaces like fiberglass mats absorb large amounts of resin and cure with ridiculously strong durability.

Deep pour epoxies are utilized for creating a thick all-epoxy finish. If you want a countertop or river table that lasts forever, we recommend buying a deep pour product on Amazon.

Sq.Ft/Cubic inches coverage calculators/Epoxy resin calculators

There are plenty of different coverage calculators online that will help you calculate epoxy coverage. Just type your dimensions into the calculator for amazing reference results. One mixed gallon of DIY tabletop epoxy typically covers 12 square feet of area at 1/8-inch thickness depending on the product, and most 1:1 epoxy kits will have requirements that you can easily read on the packaging, so a gallon of epoxy has you covered for most countertop projects.

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Supplies You’ll Need For Epoxy Projects


Use a scale to get all of your measurements correct when mixing part ‘A’ with part ‘B’. Disregard the need for a scale if you’re using a 1:1 epoxy countertop kit or JBweld.

–> Your epoxy of choice 

Finding the right epoxy for the job. Whether it’s casting resin, coating epoxies, polyester resin, or a simple set of epoxy tubes, the product you use depends on the project. 

–> Hardener/catalyst 

When buying larger quantities, the hardener comes separately. There are sometimes different types of hardeners that perform differently for different applications. The biggest variable with hardeners is dry time, and don’t forget that the more hardener you mix into your resin, the faster it will cure.

-> Fiberglass/carbon fiber

Have you considered adding a composite material to your epoxy project? Did you know that applying epoxy to a woven fabric creates a strong and contoured (if desired) finish? Products like hockey sticks, car body panels, skis, surfboards, bicycles, wheels are some examples of high-end carbon fiber products that utilize epoxy to create an ultra-strong and lightweight design.

How Much Epoxy Do I Need? (5-Step Guide)

  1. Find the right epoxy for your project

  2. Measure square footage

  3. Weigh/mix the epoxy

  4. Apply the epoxy 

  5. Sand/finish

Step 1: Find the right epoxy for your project

The right epoxy depends on what you’re working on. For example, are you looking to cover a wood countertop with a completely water-tight surface? Then you’ll want a 1:1 DIY countertop kit that can easily be purchased on websites like Amazon.

Are you making a surfboard? You’ll want polyester resin. Are you making a carbon fiber panel for an automobile? You’ll want to buy a heavy duty epoxy resin from an auto body or marine shop.

And, of course, if you’re trying to glue a pencil back together you’ll want something like JBWeld for the job. Also, epoxy putty is invaluable for piping repair and other situations (like repairing wall plaster or car dents).

Step 2: Measure the square footage & consider the thickness

Some epoxy products will have a square footage recommendation of how much to use per square foot. 

You’ll want to use a generous amount of epoxy on your project so that it cures at its maximum potential of hardness, but don’t use so much that you’re going to have to spend a lot of time sanding it off. Complete resin coverage is vital for creating

Remember that epoxy is a self-leveling liquid–that means it falls with gravity, so you’ll need to consider the thickness and parameters of where you’ll be applying the epoxy before laying it out. That also means you’ll need to consider the thickness of your fiberglass or carbon fiber weave. Thicker materials like 1 1/2 oz. glass mat will absorb a lot more epoxy compared to a 4 oz. the thickness used for building surfboards and other projects. 

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Step 3: Weigh/Mix the epoxy + prep the surface

Some epoxies need an exact amount of part ‘b’ catalyst mixed in by weight. You’ll need a scale to properly weigh each liquid, as pouring them into a measuring cup won’t exactly do the trick (epoxies have different weight densities).

Mixing the epoxy is as simple as stirring with a stick, but if you want to mix it well, you’ll use something mechanical. Try a paint mixer drill attachment the next time you mix epoxy for incredible results.

Another important factor when applying adhesives is prepping the substrate (the surface you’re applying the epoxy to). It’s important to note that epoxy/polyester resins will eat through some plastics, including polyethylene. Epoxies bond well to wood, polyurethane foam, and virtually anything else that has equal or higher surface energy than the epoxy you’re using.

Step 4: Apply the epoxy

After you’ve got your epoxy perfectly measured and mixed, it’s time to apply it to your project. How did you do? Is your epoxy cured all the way? If not, you’ll need to wait until it’s completely hard to start finishing. 

Applying epoxy to certain projects is an art. If you don’t apply it properly, it won’t cure strongly, and if you apply too much you’ll be left with excess sanding or chipping. Our best advice is to research your specific project thoroughly before applying the epoxy. Youtube has great tutorials, and the internet is packed full of composites information.

Epoxy countertops and other flatter projects typically require that you use a plastic spreader to evenly distribute the epoxy throughout the surface of the project. Other more curved surfaces like boats and automotive repair require a paint roller to press the mixed epoxy down into the surface of the fabric.

Step 5: Sand/finish 

The finishing process typically takes more time and detail than any other step in the epoxy process.

The way you finish your epoxy project depends on what you’re working on, but you’ll likely want some different grits of sandpaper and an electric orbital sander to get the smoothest finish. 

After you are satisfied with your final coat, you can wet sand the finish for an ultra-smooth texture.

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Other Valuable Resources on How Much Epoxy Do I Need

There are plenty of epoxy calculators online that will help you figure out how much epoxy you need based on the square footage and thickness of the project.

Again, we suggest doing as much research as possible before applying epoxy to yield the best results.

Meet Your Pro Paint Corner Author

Ryan Nichols

Ryan Nichols

I first painted professionally in my late teens. I have painted everything from long military base walls to spraying cedar wood siding on cabins in the mountains of Utah. I am also an automotive technician with plenty of auto body and paint experience. In my spare time, I even enjoy artistic oil painting.

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Ryan Nichols

Ryan Nichols

I first painted professionally in my late teens. I have painted everything from long military base walls to spraying cedar wood siding on cabins in the mountains of Utah. I am also an automotive technician with plenty of auto body and paint experience. In my spare time, I even enjoy artistic oil painting.

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