How to Use This Epoxy Resin Calculator
This calculator helps you determine exactly how much epoxy resin and hardener you need for your project, eliminating guesswork and reducing waste. Follow these steps:
- Select your project type. Choose from River Table, Coating/Tabletop, Mold/Casting, Art/Geode (circular), Deep Pour, or Custom. The calculator will show the appropriate dimension inputs for your project.
- Choose your unit system. Toggle between Imperial (inches) or Metric (centimeters) depending on how you've measured your project.
- Enter your dimensions. Input the length, width, and depth (or diameter for circular projects). For coatings, the default thickness is 1/8 inch—adjust as needed.
- Select your mixing ratio. Most tabletop epoxies are 1:1, while many casting resins are 2:1. Check your epoxy's instructions.
- Add cost info (optional). Enter your epoxy's price per gallon to get a cost estimate.
- Keep the waste factor checked. The 10% extra accounts for mixing residue, drips, and small spills—it's better to have extra than run short mid-pour.
Click Calculate to see your total volume needed, split between Part A (resin) and Part B (hardener), with gallon and liter conversions.
How Epoxy Resin Works
Epoxy resin is a two-part system consisting of resin (Part A) and hardener (Part B). When mixed together in the correct ratio, a chemical reaction called polymerization occurs, transforming the liquid mixture into a solid, durable plastic.
Understanding Mixing Ratios
The mixing ratio is critical to proper curing. A 1:1 ratio means equal parts resin and hardener by volume. A 2:1 ratio means two parts resin to one part hardener. Using the wrong ratio doesn't just slow curing—it can completely prevent the epoxy from hardening, leaving you with a sticky, unusable mess.
Always measure carefully. Many professionals use graduated mixing cups or digital scales for precision. Eyeballing is the most common cause of epoxy failures.
The Exothermic Reaction
The curing process generates heat—this is called an exothermic reaction. In thin pours (like coatings), this heat dissipates safely. But in thick pours or large volumes, heat can build up rapidly, causing the epoxy to cure too fast, crack, yellow, or even smoke.
This is why deep pour epoxies exist: they're formulated to cure more slowly, generating less heat over a longer period. Standard tabletop epoxy should never be poured thicker than 1/8 to 1/4 inch per layer.
Why Accurate Measurement Matters
Running out of resin mid-project is a nightmare—you can't just pour more on top of partially cured epoxy and expect it to bond properly. Conversely, buying way more than you need wastes money on a product with limited shelf life. This calculator accounts for your exact project dimensions plus a practical waste factor to ensure you order the right amount.
The formula converts your project's cubic volume to fluid ounces, then splits it according to your mixing ratio. We add 10% by default because some resin always remains in mixing containers, drips off edges, or gets used for seal coats.
Examples
Example 1: Coating a 24" × 48" Tabletop at 1/8" Thick
You're refinishing a coffee table with a glossy epoxy coating.
- Volume: 24" × 48" × 0.125" = 144 cubic inches
- Convert to fluid ounces: 144 × 0.554 = 79.8 fl oz
- Add 10% waste: 79.8 × 1.1 = 87.8 fl oz
- With 1:1 ratio: 43.9 fl oz resin + 43.9 fl oz hardener
- Total: about 0.69 gallons (2.6 liters)
You'd want to purchase at least a 1-gallon kit to have enough for the flood coat plus a thin seal coat.
Example 2: River Table Channel (6ft × 2" × 1.5")
You're filling a 6-foot river table with a 2-inch wide channel that averages 1.5 inches deep.
- Volume: 72" × 2" × 1.5" = 216 cubic inches
- Convert to fluid ounces: 216 × 0.554 = 119.7 fl oz
- Add 10% waste: 119.7 × 1.1 = 131.6 fl oz
- With 2:1 ratio: 87.8 fl oz resin + 43.9 fl oz hardener
- Total: about 1.03 gallons (3.9 liters)
You'll need a 1.5-gallon deep pour kit. Remember to pour in layers if using standard epoxy.
Example 3: 12" Diameter Geode Art Piece at 0.5" Deep
You're creating a circular resin geode on a 12-inch round canvas.
- Radius: 6 inches
- Volume: π × 6² × 0.5 = 56.5 cubic inches
- Convert to fluid ounces: 56.5 × 0.554 = 31.3 fl oz
- Add 10% waste: 31.3 × 1.1 = 34.4 fl oz
- With 1:1 ratio: 17.2 fl oz resin + 17.2 fl oz hardener
- Total: about 0.27 gallons (1 liter)
A 32-ounce (1-liter) kit would be perfect for this project with a little room for experimentation.
Frequently Asked Questions
What is the correct mixing ratio for epoxy resin?
Most epoxy resins use either a 1:1 or 2:1 mixing ratio by volume. The ratio depends on the specific product—always check your epoxy's instructions. Measuring accurately is critical: too much hardener won't make it cure faster, and incorrect ratios result in sticky, uncured resin that never fully hardens.
How long does epoxy resin take to cure?
Cure time varies by product and environmental conditions. Most table-top epoxies reach a gel state in 4-8 hours, are touchable in 24 hours, and fully cure in 72 hours to 7 days. Deep pour epoxies cure more slowly—up to 7 days for full cure. Higher temperatures speed up curing; lower temperatures slow it down.
How do I get rid of bubbles in my epoxy?
Bubbles form from mixing, porous surfaces, and temperature changes. To minimize them: warm your resin to 75-85°F before mixing, mix slowly, seal porous surfaces with a thin seal coat first, and use a heat gun or propane torch to pop surface bubbles within 20 minutes of pouring. Quick passes with heat work best—don't hold the flame in one spot.
What temperature should I work with epoxy?
Ideal working temperature is 70-80°F (21-27°C) for both the resin and your workspace. Below 60°F, epoxy becomes thick and difficult to work with, and may not cure properly. Above 90°F, it cures too quickly and may overheat. Keep your project at stable temperature for the entire cure time.
How long does unmixed epoxy last?
Unopened epoxy typically has a shelf life of 1-2 years when stored properly. Keep it in a cool, dry place away from direct sunlight. Once opened, use within 6-12 months. If your resin looks cloudy or crystallized, you can gently warm it in a water bath to restore clarity—but if it's yellowed or smells off, replace it.
Is cured epoxy food safe?
Most general-purpose epoxies are NOT food safe. If you need food-safe epoxy for cutting boards, serving trays, or cups, you must use an FDA-compliant epoxy specifically marketed as food safe. Even then, many are only food safe when fully cured (7+ days) and only for incidental contact, not for direct food storage.
Can I add color to epoxy resin?
Yes! Use pigments specifically designed for resin: mica powder, alcohol inks, liquid resin dyes, or resin-specific colorants. Avoid water-based paints or acrylics, which can prevent proper curing. Add pigments to Part A (resin) before mixing with Part B (hardener). Use no more than 6-10% colorant by weight to avoid affecting the cure.