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Epoxy Calculator

Construction

Calculate how many gallons of epoxy resin you need to coat a floor at a given thickness. Enter your area and mil thickness to get an accurate volume estimate.

55,000
0.0050.5

Gallons of Epoxy Needed

3.74
Total Volume
864

This calculator computes your Gallons of Epoxy Needed, Total Volume from the values you enter.

Inputs
Floor AreaCoating Thickness
Outputs
Gallons of Epoxy NeededTotal Volume

What is a Epoxy?

An Epoxy Calculator estimates how many gallons of epoxy resin or epoxy floor coating you need based on the surface area you're covering and the thickness of the application. Because epoxy is a liquid measured by volume, coverage depends on both square footage and how thick a layer you're pouring — a thin garage floor coating and a thick bar-top pour over the same footprint require very different amounts of material.

Epoxy flooring and resin projects are popular for garages, basements, workshops, and decorative surfaces across the US, but material ordering is one of the trickiest parts of the job. Unlike paint, where coverage is usually quoted per gallon regardless of thickness, epoxy thickness is often specified in mils (thousandths of an inch), and getting the volume math wrong can mean running out mid-pour — a serious problem since epoxy cures quickly once mixed. This calculator converts your area and thickness directly into the gallons you need to buy.

If you're finishing a wood deck rather than a concrete or resin surface, the Deck Stain Calculator handles that coverage math instead.

How to use this Epoxy calculator

  1. Measure your floor or surface and enter the total square footage in the Floor Area field.
  2. Check your epoxy product's recommended mil thickness and convert it to inches (divide mils by 1,000), then set the Coating Thickness slider to that value.
  3. Review the Gallons of Epoxy Needed result for the amount to purchase.
  4. Check the Total Volume figure in cubic inches if you need to cross-reference the manufacturer's coverage specifications.
  5. Adjust the thickness slider to compare how a thicker or thinner application changes your total material cost.
  6. If your project uses multiple coats, repeat the calculation for each coat's thickness and add the gallon totals together.

Formula & Methodology

The calculator converts area and thickness into volume, then into gallons using the standard US liquid volume conversion:

Volume (in³) = Area (sq ft) × 144 (in²/sq ft) × Thickness (in)

Gallons Needed = Volume (in³) ÷ 231 (in³ per US gallon)

Worked example: For a 200 sq ft floor at a 0.03 inch (30-mil) thickness:

- Volume = 200 × 144 × 0.03 = 864 in³
- Gallons Needed = 864 ÷ 231 ≈ 3.74 gallons

So you'd need approximately 3.74 gallons of mixed epoxy for this coating.

Frequently Asked Questions

For a 200 sq ft floor at a typical 30-mil (0.03 inch) coating thickness, you need about 3.74 gallons of epoxy. The calculator converts your area and thickness into cubic inches of volume, then divides by 231 cubic inches per US gallon to give you an exact gallon figure.
Volume in cubic inches equals area in square feet multiplied by 144 (converting square feet to square inches) multiplied by thickness in inches. Gallons needed equals that volume divided by 231, since one US gallon contains exactly 231 cubic inches.
Most residential garage floor coatings are applied at 10 to 20 mils (0.01 to 0.02 inches) per coat, while thicker flooring systems like epoxy terrazzo or heavy-duty industrial floors can run 30 to 125 mils. Check your specific product's technical data sheet, since coverage varies significantly between flooring-grade epoxy and countertop or tabletop epoxy resin.
A basic epoxy coating is typically a single or double coat applied directly over prepared concrete at a thin mil thickness, mainly for protection and light color. A full epoxy resin flooring system often includes a primer, a thicker build coat, and a topcoat or broadcast media, so total material needed is the sum of each individual layer's volume.
Mils (thousandths of an inch) are the industry-standard unit for coating thickness because epoxy layers are very thin relative to an inch — a 30-mil coat is only 0.03 inches thick. This calculator accepts thickness directly in inches, so convert your product's mil rating by dividing by 1,000 before entering it (30 mils = 0.03 inches).
No, the output represents the theoretical volume needed to cover the stated area at the stated thickness with no waste factored in. In practice, contractors commonly add 10 to 15 percent extra to account for mixing residue left in containers, uneven pours, and surface porosity in the substrate.
Enter your floor's square footage in the Floor Area field, then set the Coating Thickness slider to match your product's recommended mil rating converted to inches. The calculator instantly shows the gallons of epoxy needed along with the total volume in cubic inches.
A common rule of thumb in the US flooring industry is that 1 gallon of epoxy covers roughly 1,600 square feet at 1 mil thickness, which scales down proportionally as thickness increases. At a 30-mil application, that same gallon covers only about 53 square feet, which is why thickness has such a large impact on total gallons needed.
Yes, the volume math is identical for any epoxy product measured by liquid volume, whether it's a two-part resin and hardener system for countertops or a flooring-grade epoxy coating. Just make sure you're using the total mixed volume thickness, not the thickness of a single component before mixing.
Bar tops and tabletops are typically poured much thicker than floor coatings, often at 1/8 inch (0.125 inches) or more per pour to achieve a glossy, self-leveling finish. Enter your surface area and set the thickness slider accordingly — a 20 sq ft bar top at 0.125 inches needs roughly 1.56 gallons.
Many epoxy flooring systems use two or more coats — a base coat and a topcoat — each with its own thickness and coverage requirements. Calculate each coat separately using its specific thickness, then add the gallon totals together for your full material order.
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