Epoxy Floor Coating Calculator
Gallons of epoxy for a garage or basement floor, by coats.
Most floors get a primer or base coat plus a top coat.
From the kit. Water-based: 200 to 300. 100% solids: 80 to 100.
You need
3.2 gallons
Round up to whole kits. Mixed epoxy cannot be saved for later.
- Floor area
- 400 sq ft
- Total area to coat
- 800 sq ft
Estimates only. Verify quantities before ordering.
How this is calculated
Gallons = floor area x coats / coverage per gallon. A standard 2-car garage is about 400 to 500 sq ft; check your kit's stated coverage and buy whole kits.
Enter the floor dimensions, the number of coats, and the coverage rate from your product, and this calculator returns the gallons to buy. Epoxy is usually sold as two-part kits sized in half-gallon and gallon units of mixed product, and the box states its coverage for one coat, which is the number to enter here.
Coverage varies by chemistry more than any other coating. Water-based epoxy paints spread thin and cover 200 to 300 square feet per gallon, while high-build 100% solids epoxies go on thick and may cover only 80 to 100. Rough or porous concrete drinks more in the first coat, and broadcast color flakes or anti-slip grit do not change the liquid math.
Epoxy for common floor sizes
Rows assume two coats at 250 sq ft per gallon. Round up to whole kits.
| Floor | Gallons | Area |
|---|---|---|
| 12 x 22 ft (1-car garage) | 2.1 gallons | 264 sq ft |
| 20 x 20 ft (2-car garage) | 3.2 gallons | 400 sq ft |
| 24 x 24 ft (large 2-car) | 4.6 gallons | 576 sq ft |
| 30 x 24 ft (3-car garage) | 5.8 gallons | 720 sq ft |
| 30 x 40 ft (shop floor) | 9.6 gallons | 1,200 sq ft |
Common questions
How much epoxy for a 2-car garage?
A typical 2-car garage floor is 400 to 500 square feet. At 250 square feet per gallon that is about 2 gallons per coat, so a primer coat plus top coat needs around 4 gallons. Most brands sell a 2-car kit per coat; buy two kits for a two-coat system.
Why did my epoxy kit not cover what the box said?
Stated coverage assumes smooth, sealed concrete. Bare or acid-etched concrete absorbs a lot of the first coat, and rough-troweled or pitted floors add surface area. Plan on the low end of the stated range for the first coat; the second coat usually hits the rated number.
Do I need to etch or grind the floor first?
Yes, surface prep decides whether epoxy lasts. The concrete must be clean, dry, and profiled: diamond grinding is best, acid etching is the common DIY route. Test for moisture by taping down a plastic square overnight; condensation underneath means the slab needs a moisture-tolerant primer or should not be coated.
What is the difference between epoxy paint and real epoxy?
One-part 'epoxy paints' are latex with a small epoxy additive: cheap, thin, and short-lived under tires. True two-part epoxy cures chemically after you mix resin and hardener, builds a much thicker film, and resists hot-tire pickup. The two-part product is what the coverage numbers here assume.