How much epoxy for a 20 × 20 two-car garage?
You need 2 kits of garage floor epoxy rated at 250 square feet per coat for a 20 × 20 ft two-car garage (400 square feet), since one coat plus a 10% margin is 440 square feet. Buying a 100%-solids coating by the gallon instead, it’s about 2.87 gallons per coat at 10 mils with 15% waste — see How many gallons of floor epoxy for 400 sq ft at 10 mils.
How to work it out
- 20 ft × 20 ft = 400 sq ft × 1 coat + 10% = 440 sq ft
- 440 sq ft ÷ 250 sq ft per kit = 1.76 → 2 kits
- Section per kit: 250 sq ft ÷ 1.1 = 227 sq ft
Twenty by twenty is the smallest common two-car garage. Two 250 sq ft kits cover it with about 60 sq ft to spare, which is useful: tire paths and the apron at the door usually take a little extra.
Adjust for your project
More options: waste · $/kit
- Floor area
- 400 sq ft
- Coverage needed (all coats + waste)
- 440 sq ft
- Spare coverage in the last kit
- 60 sq ft
- Area one kit covers per coat
- 1 kit ≈ 227 sq ft per coat — chalk-line the floor into sections this size
- Kit coverage assumes clean, properly prepared concrete. Old, porous or etched floors can drink noticeably more of the first coat.
Kits for a 20 × 20 ft garage by number of coats (250 sq ft kits)
| Coats | Coverage needed (all coats + waste) | Kits to buy | Spare coverage in the last kit |
|---|---|---|---|
| 1 coat | 440 sq ft | 2 kits | 60 sq ft |
| 2 coats | 880 sq ft | 4 kits | 120 sq ft |
| 3 coats | 1,320 sq ft | 6 kits | 180 sq ft |
What to know about a 20 × 20 two-car garage
Two kits leave about 60 sq ft of slack — roughly 14% of the floor. That’s a comfortable cushion for a clean, ground slab, but it disappears fast on old, dusty concrete that soaks up the first coat. If the floor has never been coated and water darkens it instantly, treat the slack as already spent and don’t stretch the rolled film to make it reach.
The size is a threshold. A 22 × 20 ft floor still fits two kits (about 484 sq ft of coverage with the margin), but 22 × 22 ft needs about 532 sq ft and tips into a third box. Many “two-car” garages are a foot or two bigger than 20 × 20 once you measure into the corners, so measure before you order.
With two cars on it, the wear is concentrated in four tire tracks and the strip at the door. Hot tires can peel up a coating that hasn’t cured or wasn’t bonded well; Garage Flooring LLC’s instructions suggest waiting about a week before parking on a new floor.
For the roomier size with a flake finish, see How much epoxy for a 24×24 garage floor. For a narrower single bay, see How much epoxy for a 1-car garage floor.
Different size? Use the full Garage Floor Epoxy Calculator.
What you’ll need
- Garage floor epoxy kitPremium price
Boxed kits usually include the base coat and sometimes etch and flakes. Check coverage per coat and what’s actually in the box.
See options on Amazon (opens in a new tab) - Epoxy roller kit (3/8 in nap)Budget price
Shed-resistant roller covers, frame and tray. Have spare covers — a roller that starts to gel is done.
See options on Amazon (opens in a new tab) - Spiked shoesBudget price
Strap-on spikes let you walk across a wet coat to broadcast flakes or back-roll without leaving footprints.
See options on Amazon (opens in a new tab)
As an Amazon Associate we earn from qualifying purchases. Links to products are affiliate links — they cost you nothing extra and help keep these calculators free.
Frequently asked questions
How many kits for two coats on a 20 × 20 garage?
Two coats need 880 square feet of coverage with a 10% margin, so 4 kits rated at 250 square feet.
Does one 500 sq ft epoxy kit cover a 20 × 20 ft garage?
Yes — one coat with the margin needs 440 square feet, so 1 kit rated at 500 square feet covers it with 60 square feet left over.
How many pounds of flakes for a 20 × 20 ft garage floor?
About 66 pounds for a full broadcast at a mid-range 15 lb per 100 square feet, including the 10% margin — 2 boxes of 40 lb.
Other common sizes
Sources
- Garage Flooring LLC — Garage Floor Epoxy Coating Instructions (opens in a new tab) — Plastic-sheet moisture test, grinding or etching, light traffic after about 72 hours and about a week before parking.
- Spartan Epoxies — Purchase epoxy by layer (opens in a new tab) — Floor-coating coverage per gallon at a given mil thickness.
- Concrete Floor Supply — Epoxy flake calculator (opens in a new tab) — Full coverage: about 0.10 lb/sq ft for 1/4 in flakes, about 0.20 lb/sq ft for 1/8 in flakes.
- WALT Tools — Flake flooring (opens in a new tab) — Vinyl chips planned at about 8 sq ft per lb for a full broadcast; real-world use about 5–10 sq ft per lb depending on chip size and throwing.
- Legacy Industrial — ColorFlake decorative chips (opens in a new tab) — Chips sold in 10, 20, 30 and 40 lb quantities; custom blends in 40 lb increments.
- US EPA — Volatile Organic Compounds’ Impact on Indoor Air Quality (opens in a new tab) — Increase ventilation when using products that emit VOCs.