Epoxy Floor Calculator
Calculate how many gallons of mixed epoxy coating you need for a garage or shop floor, plus total cost.
How this calculator works
Mixed epoxy floor coating typically covers about 250 square feet per gallon for a standard garage floor system. This calculator multiplies floor length by width to get total area, then divides by 250 sq ft per gallon.
Formula: Gallons = Floor area (sq ft) ÷ 250 sq ft per gallon.
Worked example
A 24 ft × 20 ft two-car garage (480 sq ft):
- Area: 24 × 20 = 480 sq ft
- Gallons: 480 ÷ 250 = 1.92 gallons
- At $120/gallon, that’s $230.40.
Coverage reference
| Floor area | Gallons needed |
|---|---|
| 120 sq ft | 0.48 gallons |
| 480 sq ft | 1.92 gallons |
| 1,920 sq ft | 7.68 gallons |
How to measure your floor
Measure the length and width of the garage, shop, or basement floor in feet, including any storage alcoves or extensions being coated. Confirm your kit’s specific coverage rate against the 250 sq ft/gallon this calculator assumes, since decorative flake or metallic systems often specify a thicker (and lower-coverage) application.
Frequently asked questions
How much floor does one gallon of mixed epoxy cover?
About 250 square feet per gallon of mixed (Part A + Part B combined) epoxy for a standard single-coat garage floor system. This calculator uses that 250 sq ft/gallon rate — always check your specific kit's coverage spec, since thicker or metallic-flake systems cover noticeably less area.
Why is a 24 ft x 20 ft the default size for this calculator?
That's a common footprint for a standard 2-car garage, which is the single most common epoxy flooring project. Enter your actual garage or shop dimensions if they differ — a 3-car garage or a small workshop will need a proportionally different gallon count.
Why does floor prep matter more for epoxy than for paint?
Epoxy chemically bonds to concrete, and any residual sealer, oil, grease, or moisture in the slab will cause the coating to peel or delaminate within months rather than years. Proper prep — degreasing, acid-etching or grinding, and confirming the slab isn't wicking moisture — is what separates a floor that lasts a decade from one that fails in a season.
Do I need a moisture test before applying epoxy over concrete?
Yes, especially on a slab-on-grade garage or basement floor — a calcium chloride or relative humidity moisture test tells you whether vapor is moving up through the slab, which can cause epoxy to bubble or peel even over an otherwise well-prepped floor. Some products offer moisture-tolerant formulations for borderline readings.
Why is there no waste toggle for epoxy floor coating?
Epoxy is mixed in batches and rolled across the entire floor at a set coverage rate rather than cut and pieced, so there's minimal material waste beyond what's left in the mixing bucket — the main variable to plan for is having enough extra to avoid running out mid-pour, since epoxy has a limited working (pot) time once mixed.
Estimates only. Verify quantities with your supplier before purchasing.