Epoxy Floor Calculator

How Epoxy Coverage Really Works

Every epoxy coating starts from the same physical fact: one gallon spread one mil thick covers about 1,604 square feet. Thickness is what changes everything. Roll that same gallon to a 12-mil garage finish and it only reaches around 133 square feet. Take a 400 sq ft garage at roughly 12 mils and you need about 3 gallons per coat — run the standard two coats and that is close to 6 gallons of product, before you add primer. This calculator turns your area, target mils, and coat count into a gallon figure so you order once instead of driving back for another kit.

Thickness, Coats, and Why the Label Lies a Little

Kit boxes advertise coverage at the thinnest film the product will form, so a box that says 500 sq ft is often assuming a single 5-mil pass. Most real garage jobs want more film than that: a primer coat to grip the concrete, then a color coat rolled to 10–12 mils for durability. Two coats roughly doubles your gallons, and bare or freshly ground concrete soaks up the first coat, cutting effective coverage 20–30%. That gap between the label number and the real number is exactly where people run short.

Thin Coat vs. Self-Leveling

There are two very different products behind the word epoxy. A rolled thin coat lands at 5–12 mils and covers a few hundred square feet per gallon — this is what most garages and workshops use. A self-leveling pour is applied at 1/8 to 1/4 inch, so a single gallon only covers 12–16 square feet. On the same 400 sq ft floor, a thin two-coat job might be 6 gallons while a 1/8-inch self-leveling floor is closer to 28–36 gallons. Pick the coating type in the calculator first, because it swings the total by an order of magnitude.

How to Use This Calculator

1. Enter your floor area: Type the square footage directly, or switch to length × width and enter the bay dimensions — a 22 × 20 garage is 440 sq ft. Measure to the wall, not the parked-car footprint.
2. Pick the coating type: Thin coat for a rolled garage or workshop finish, self-leveling for a poured 1/8-inch floor, or decorative flake for a chip-broadcast system. This sets the coverage rate the math uses.
3. Set the number of coats: Two coats is the norm for a garage: primer or base plus a color coat. Add a third for a clear topcoat over high-traffic or flaked floors. One coat is usually only enough for a light basement seal.
4. Read gallons, kits, and primer: The result shows total gallons for all coats, how many kits that is, and a separate primer figure. Add your price per gallon to see the material cost, and round gallons up so you finish every coat wet.

Tips & Considerations

• Order 10–15% more than the calculator shows. Overlap at walls, refilling the roller tray, and pot life waste all eat into your gallons, and you cannot pause a coat to buy more.
• Bare concrete is thirsty. A freshly acid-etched or ground slab can pull the first coat down to 70–80% of its rated coverage, so treat primer coverage as a range, not a promise.
• Two thin coats beat one thick one. Epoxy rolled too heavy in a single pass traps solvent and can blush or peel — build your mils across coats instead.
• Match kit chemistry to the job: water-based epoxy films thinner (5–8 mils) than 100%-solids products (10–15+ mils), so the same square footage needs different gallons.
• Do not skip primer on porous or previously coated concrete. It anchors the color coat and stops pinholes from outgassing, and it is cheaper per gallon than the finish coat it protects.