Epoxy Calculator

By Uzair Arshad , Senior Civil and Structural Engineer

Last updated: April 26, 2026

This epoxy calculator estimates how much epoxy resin you need for tabletops, countertops, river tables, flood coats, and deep pours. Enter your project shape, dimensions, and thickness to get gallons, fluid ounces, and milliliters with optional seal coat, edge overflow, and waste adjustments.

How to use this calculator

Choose the project shape. The epoxy calculator supports two shapes. Select rectangle for tables, countertops, and bar tops. Select round for circular tabletops, clock faces, and trays.
Enter dimensions. For rectangles, enter length and width in inches. For round projects, enter the diameter in inches. Measure at the widest points and use the same unit for all fields.
Select the epoxy thickness. Use 1/8 in for a standard flood coat on a flat surface. Use 1/4 in for a thicker topcoat. Choose 1/2 in or deeper for casting and deep pour projects.
Set edge handling. Choose "Dam or tape the edges" if you plan to contain the resin with painter's tape or a silicone dam. Choose "Let epoxy overflow" if the resin will run over the sides, which uses about 15% more material.
Toggle the seal coat. Turn this on if the surface is porous, such as raw wood, old barn wood, concrete, cork, or cracks. A seal coat soaks into the grain and prevents air bubbles from rising through the flood coat. The calculator adds about 2 fluid ounces per square foot.
Choose a waste factor. Keep it at 10% for most projects. Increase to 15% or 20% for rough edges, deep voids, or your first pour. The epoxy calculator adds the waste percentage to your total automatically.

Pro tip: running out of epoxy mid pour leaves a visible seam that's hard to fix. Use the epoxy calculator's waste adjusted total when ordering so you have enough resin to finish in one session. Leftover mixed epoxy can coat the underside or legs.

How the calculation works

Rectangular projects:
Volume (in³) = Length (in) × Width (in) × Thickness (in)

Round projects:
Volume (in³) = Radius² × 3.1416 × Thickness (in)

Unit conversions:
Fluid ounces = Volume (in³) / 1.805
Gallons = Fluid ounces / 128

Adjustments:
Seal coat = Surface area (sq ft) × 2 fl oz
Edge overflow = Subtotal × 1.15
Waste = Subtotal × (1 + Waste % / 100)

Length: Project length in inches
Width: Project width in inches
Diameter: Project diameter in inches (round shapes)
Thickness: Epoxy pour depth in inches
Waste factor: Extra percentage for mixing loss, drips, and uneven surfaces

The epoxy calculator finds volume in cubic inches, then converts to fluid ounces and gallons using industry standard ratios. Use this epoxy resin calculator for tabletop flood coats, deep pour projects, bar top epoxy coverage, and countertop resurfacing.

Main formulas:

Rectangular projects:

Volume (in³) = Length (in) × Width (in) × Thickness (in)

Round projects:

Volume (in³) = Radius (in) × Radius (in) × 3.1416 × Thickness (in)

Conversions:

Fluid ounces = Volume (in³) / 1.805 (one US fluid ounce equals 1.805 cubic inches by definition)

Gallons = Fluid ounces / 128

Variables:

Length = project length in inches (rectangle mode)
Width = project width in inches (rectangle mode)
Diameter = full diameter of the round surface in inches (round mode)
Thickness = epoxy pour depth in inches (1/8 in for flood coats, 1/2 in to 2 in for deep pours)
Seal coat = adds about 2 fl oz per square foot for porous surfaces like raw wood, concrete, or cork
Edge overflow = multiplies the subtotal by 1.15 because resin coats the sides and drips under the lip
Waste factor = extra percentage for mixing loss, drips, uneven surfaces, and container residue

Example:

A 48 in × 24 in tabletop at 1/8 in thickness with 10% waste and no seal coat.

Step	Calculation
Volume	48 × 24 × 0.125 = 144 in³
Fluid ounces	144 / 1.805 = 79.8 fl oz
Gallons	79.8 / 128 = 0.62 gal
With 10% waste	79.8 × 1.10 = 87.7 fl oz (0.69 gal)

Assumptions and limitations:

Porous surfaces absorb resin. Raw wood, barn wood, cork, and concrete should get a seal coat first to prevent bubbles from rising through the flood coat.
Edge overflow assumes about 15% more material. Actual usage depends on edge thickness, drip length, and whether the underside is coated.
Deep pours above 1/4 in often need staged sessions. Most epoxy products have a maximum pour depth per session (typically 1/4 in to 1 in). Check your product label and pour in layers if the total depth exceeds that limit.
Use the two cup mixing method: mix resin and hardener in one cup, then pour into a clean cup and mix again. Scrape the sides and bottom so the epoxy cures evenly without soft spots.
Cooler work areas slow curing. Follow the manufacturer's recommended temperature range (usually 70°F to 85°F) for consistent results.

Frequently Asked Questions

How much epoxy do I need?

Multiply length × width × thickness in inches to get cubic inches, then divide by 1.805 for fluid ounces and by 128 for gallons. A 48 in × 24 in tabletop at 1/8 in thickness needs about 80 fluid ounces before waste. Add 5% to 10% extra for mixing loss and drips.

How do you calculate an epoxy pour?

Calculate an epoxy pour by finding volume first. For a rectangle, multiply length × width × pour depth in inches. For a round surface, use radius × radius × 3.1416 × depth. Convert cubic inches to fluid ounces by dividing by 1.805. Add 5% to 10% for mixing loss, drips, and uneven surfaces.

How do you calculate epoxy coverage?

Epoxy coverage depends on thickness, not just square footage. A thin 1/8 in flood coat covers far more area per gallon than a 1 in deep pour. Enter your surface dimensions and thickness in the epoxy calculator, then review gallons, fluid ounces, and the waste adjusted total before ordering.

How do you calculate epoxy for a river table?

For a river table, calculate only the river channel volume, not the full tabletop. Measure the average river width, length, and depth in inches. A 60 in × 6 in × 1.5 in channel equals 540 cubic inches before waste. Add 10% to 15% extra for voids, bark edges, and uneven surfaces.

How do you calculate epoxy resin volume?

Epoxy resin volume equals length × width × depth for rectangles, or radius × radius × 3.1416 × depth for round projects. Keep all measurements in inches. Divide cubic inches by 1.805 to get fluid ounces, then divide by 128 for gallons. Always add waste for mixing and surface irregularities.