Epoxy Resin Calculator

There's a special kind of frustration that comes with running out of epoxy halfway through a pour. You're watching your beautiful river table develop a hard line right down the middle, knowing that seam will haunt you forever. Or worse—you've bought three gallons too many and now you're the proud owner of $150 worth of resin that'll cure in the bottles before your next project.

Neither scenario is fun. This calculator exists to prevent both.

Tell us your project dimensions and coating thickness, and we'll tell you exactly how much mixed epoxy to buy. Works for countertops, river tables, artwork, garage floors, or that cutting board you've been meaning to seal for six months. No more guessing, no more math on the back of a napkin, no more "I think two gallons should be enough?"

Epoxy is a two-part system: resin and hardener. Mix them together and a chemical reaction kicks off that transforms the liquid into a rock-hard, glossy, waterproof surface. Most products use either a 1:1 or 2:1 mixing ratio—check your bottles.

Here's the thing about epoxy that trips people up: once you mix it, you're on the clock. You've got maybe 20-45 minutes before it starts thickening in your cup. Mix too much? You can't save it for later. Mix too little? You can't exactly pause mid-pour to run to the hardware store.

That's why calculating the right amount matters more with epoxy than almost any other material. Wood stain, you can always grab another can. Paint, no problem. Epoxy? It's a one-shot deal.

Good news: the calculation itself is simple geometry.

Volume = Length × Width × Thickness

That's it. You're finding the volume of a very flat box.

Let's run the numbers on a real example:

Say you're coating a desktop that's 48 inches long and 24 inches wide, and you want a standard 1/8-inch self-leveling coat.

48 × 24 × 0.125 = 144 cubic inches

Now for the unit conversion (this is where most people's eyes glaze over, but stay with me):

• 144 cubic inches = 2,360 ml
• 2,360 ml = 80 fluid ounces
• 80 fluid ounces = about 2/3 of a gallon

So for that desktop, you'd need roughly 2/3 gallon of mixed epoxy. In practice? Buy a full gallon. Here's why.

Epoxy has a talent for disappearing. It soaks into wood grain. It finds hairline cracks you didn't know existed. It creeps over edges and drips down sides. It clings stubbornly to mixing cups and stir sticks.

That "exact" amount you calculated? It's the theoretical minimum for a perfectly sealed, laser-flat surface in a laboratory. Your garage workbench is not a laboratory.

Add 10-15% to every calculation. Leftover epoxy can become coasters, test pieces, or practice pours. Running short means visible seam lines, thin spots, or an emergency second pour that never quite matches the first.

1. Enter your coating thickness Thin seal coat? That's about 1/16" (1.5mm). Standard tabletop flood coat? Go with 1/8" (3mm). Filling a river channel? You're looking at 1-2" with deep pour epoxy.

2. Pick your surface shape Rectangular covers most projects—tables, counters, floors, cutting boards.

3. Punch in your dimensions Length and width. Measure twice. Seriously. Being off by 2 inches on a 4-foot table throws your calculation off by a surprising amount.

4. Choose your units Get results in ml, fluid ounces, liters, or gallons—whatever matches how your epoxy is sold.

5. Add your buffer Take the result, add 10-15%, and that's your shopping list.

Let's walk through five actual projects so you can see what you're dealing with.

Project: Coating a 6-foot × 3-foot dining table with a 1/8" flood coat

The math: 72" × 36" × 0.125" = 324 cubic inches = 5,310 ml (1.4 gallons)

What to buy: 1.5 to 2 gallons, depending on how porous your wood is. Old farmhouse tables drink epoxy like they've been in a drought. Sand to 220 grit and do a thin seal coat first—it'll save you resin in the long run.

Project: Filling an 8-foot walnut slab with a 6-inch wide, 1.5-inch deep river channel

The math: 96" × 6" × 1.5" = 864 cubic inches = 14,160 ml (3.7 gallons)

What to buy: 4-5 gallons of deep pour epoxy (not regular tabletop epoxy—this is critical)

Why it matters: Standard epoxy poured this thick will heat up, potentially crack, yellow, or in extreme cases, actually smoke. Deep pour formulas cure slower and stay cool. Yes, they cost more. Yes, it's worth it. That walnut slab wasn't cheap either.

Project: Batch of 12 round coasters, 4" diameter, 3/8" thick

The math per coaster: π × 2² × 0.375 = 4.7 cubic inches For all 12: 56.5 cubic inches = 926 ml (31 oz)

What to buy: A 32 oz kit handles the batch with a tiny bit left over—perfect for fixing any coasters that get bubbles or dust.

Pro tip: Pour all 12 at once if you can. Same batch means identical color and cure. And when you're selling on Etsy, consistency matters.

Project: Coating a 20' × 22' two-car garage with a 1/16" seal coat

The math: 240" × 264" × 0.0625" = 3,960 cubic inches = 64.9 liters (17.1 gallons)

What to buy: 20 gallons minimum. Concrete is porous and uneven. Some areas will take more than others.

Reality check: Garage floors are a commitment. You'll need to etch or grind the concrete first, and the floor can't be driven on for at least 72 hours (check your product specs). But once it's done? No more oil stains soaking in, easy cleaning, and that satisfying glossy showroom look.

Project: Sealing an 18" × 12" maple cutting board with a thin protective coat (1/32")

The math: 18" × 12" × 0.03125" = 6.75 cubic inches = 111 ml (3.7 oz)

What to buy: The smallest food-safe epoxy kit you can find, usually 8 oz. You'll have extra, but there's no smaller option.

The important part: Only use FDA-compliant food-safe epoxy for cutting boards. Regular epoxy is not food safe once cured, despite what some forums claim. Check the label. If it doesn't explicitly say food-safe, it isn't.

Using tabletop epoxy for deep pours Tabletop epoxy is designed for thin coats—1/4" maximum. Pour it 2 inches thick and you've got a chemistry experiment on your hands. The exothermic reaction generates serious heat. Best case: yellowing and internal cracks. Worst case: a smoking, ruined mess and a potential fire hazard. Use deep pour epoxy for anything over 1/4" thick.

Skipping the seal coat Wood has air trapped in its grain. When you pour epoxy, that air wants out—and it rises as bubbles through your beautiful flood coat. A thin seal coat applied first lets you torch out bubbles while there's barely any resin to ruin. Then your flood coat goes on bubble-free.

Calculating for one coat when you need two Some projects need a seal coat plus a flood coat. Some need multiple flood coats for depth. Make sure your calculation covers everything, not just the final layer.

Trusting your eye instead of a tape measure "About three feet" is not a measurement. Every inch matters. Pull out the tape measure, write down the numbers, and calculate from actual dimensions.

Mixing in the wrong conditions Epoxy doesn't like cold. Below 70°F, it gets thick, doesn't level well, and takes forever to cure. Too hot and your working time shrinks dramatically. The sweet spot is 70-80°F. Check your garage temperature before you start.

Rectangular surfaces: Volume = Length × Width × Depth

Circular surfaces: Volume = π × Radius² × Depth

Conversions:

• 1 cubic inch = 16.39 ml = 0.55 fl oz
• 1 gallon = 128 fl oz = 3,785 ml
• 1 liter = 33.8 fl oz = 1,000 ml

This calculator gives you total mixed volume—resin plus hardener combined. Divide according to your product's mix ratio (1:1 or 2:1) when purchasing.