Epoxy Floor Calculator
Calculate how many gallons of epoxy floor coating you need for a garage or basement from the floor size, number of coats and coverage per gallon, plus kits and flakes.
By CalcBuilt Editorial TeamUpdated September 9, 2026Formulas checked against manufacturer specs, see how we calculate.
Results
- Epoxy needed
- 3.52 gal
- 3.2 gal for 2 coats at 250 sq ft per gallon, plus 10% waste
- Kits to buy
- 2 kits of 3 gal
- 6 gal purchased. Kits are labeled by mixed volume, so check the can
- Decorative flakes
- 0 lb
- No flakes selected
- Floor area
- 400 sq ft
- 800 sq ft of total coverage across 2 coats
Epoxy Floor formula
Floor area (sq ft) = Length (ft) x Width (ft)
Gallons = Floor area x Coats / Coverage per gallon x (1 + waste %)
Kits = Gallons / Kit size, rounded up
Flakes (lb) = Floor area / 100 x broadcast rate (light 0.5 lb, full 10 lb per 100 sq ft)Worked example
A 24 x 24 ft two-car garage coated with a 100% solids kit rated at 200 sq ft per gallon, two coats: 24 x 24 = 576 sq ft. 576 x 2 / 200 = 5.76 gallons. Add 10% waste: 5.76 x 1.1 = 6.34 gallons. With 3 gallon kits, 6.34 / 3 = 2.11, so buy 3 kits.
For a full flake broadcast on the same floor: 576 / 100 x 10 = 57.6 lb of flakes, so buy 60 lb. A light sprinkle would need only 576 / 100 x 0.5 = 2.9 lb.
Quick reference
| Floor | Area | Gallons | 3 gal kits |
|---|---|---|---|
| 12 x 22 ft one-car garage | 264 sq ft | 2.32 | 1 |
| 20 x 20 ft two-car garage | 400 sq ft | 3.52 | 2 |
| 22 x 22 ft garage | 484 sq ft | 4.26 | 2 |
| 24 x 24 ft garage | 576 sq ft | 5.07 | 2 |
| 30 x 22 ft three-car garage | 660 sq ft | 5.81 | 2 |
| 30 x 40 ft basement | 1,200 sq ft | 10.56 | 4 |
How to calculate epoxy for a floor
Measure the floor length and width and multiply for the area; the whole slab gets coated, so there is nothing to subtract. Multiply the area by the number of coats, then divide by the coverage rate on the kit. Coverage is the number that matters most: a thick 100% solids product at 10 mils only spreads about 160 sq ft per gallon, while a thin water-based kit can stretch to 300. Using the kit's own figure rather than a generic one keeps you from running out halfway across the floor.
Add 10% for waste. Bare concrete is porous and drinks up more of the first coat than the label assumes, and a few ounces always stay in the mixing bucket and roller. Because a two-part epoxy has a pot life of about 30 to 45 minutes once mixed, buy whole kits and mix only what you can roll out in that window.
Prep, kits and flakes
Surface prep decides whether the coating lasts. Degrease the slab, then etch with an acid wash or, better, grind it to open the surface, and let it dry fully. Test for moisture by taping a square of plastic to the floor overnight; condensation under it means the slab needs a moisture-blocking primer or should not be coated with epoxy at all.
Garage kits are labeled by mixed volume, most often 3 gallons for a single coat on a two-car garage. Broadcast flakes into the wet base coat, scrape off the loose ones the next day, and seal with a clear top coat; a full broadcast uses about 10 lb of flakes per 100 sq ft, a light sprinkle about half a pound. Read the temperature range on the label, since most epoxies will not cure properly below 55 F (13 C).
Key facts
- One gallon of any coating covers 1,604 sq ft at 1 mil thick, so coverage per gallon equals 1,604 divided by the wet film thickness in mils.
- 100% solids epoxy applied at 10 mils covers about 160 sq ft per gallon; thin water-based garage kits spread to 250 to 300 sq ft per gallon.
- A standard two-car garage is about 20 x 20 ft, or 400 sq ft; a 24 x 24 ft garage is 576 sq ft.
- Vinyl flakes are broadcast at roughly 0.5 lb per 100 sq ft for a light accent and 8 to 10 lb per 100 sq ft for full coverage.
- Most epoxy floors accept foot traffic after 12 to 24 hours and vehicles after 3 to 7 days of cure, depending on temperature.
Frequently asked questions
How much epoxy do I need for a 2-car garage?
A 20 x 20 ft garage is 400 sq ft. At 250 sq ft per gallon, two coats take 3.2 gallons, or about 3.5 gallons with 10% waste, so plan on two 3 gallon kits, one per coat.
How many square feet does a gallon of epoxy cover?
It depends on the film thickness: 1,604 sq ft at 1 mil, so 160 sq ft at 10 mils for a 100% solids product and roughly 250 to 300 sq ft for a thin water-based kit. Always use the coverage printed on your kit.
Do I need two coats of epoxy?
Most floors get a colored base coat and a clear top coat, which is two coats. A single coat of a thin water-based kit wears quickly under tires, so count on two and add a primer on bare, porous concrete.
How many pounds of flakes do I need?
About 0.5 lb per 100 sq ft for a light accent and 10 lb per 100 sq ft for full coverage where no base color shows through. A 400 sq ft garage takes 2 lb light or 40 lb full.
Sources and references
- EpoxyShield Garage Floor Coating kit product page (Rust-Oleum)
- Calculating coating requirements: 1,604 sq ft per gallon at 1 mil (Dampney)
- What's a mil? Coverage per gallon by film thickness (Seal-Krete (Rust-Oleum))
- ArmorSeal 1000 HS epoxy floor coating product page (Sherwin-Williams)
Next steps for this project
The usual order for a flooring & tile project. See all flooring & tile calculators.
Results are estimates based on standard formulas and typical product specifications. Confirm quantities with your supplier and local code before ordering.