How Much Epoxy Do I Need? Coverage, Mils and the Math
One gallon of 100% solids epoxy covers 1,604 sq ft at 1 mil. At the 14 mils a B-707 High Build Epoxy base coat goes on, that is about 115 sq ft per gallon, so one 3 gal kit covers one car bay of 350 sq ft. A 2-car garage takes two kits, a 3-car garage three. The epoxy calculator runs the same math from your measurements.
The formula
A gallon is 231 cubic inches. Spread 1 mil thick (0.001 inch), it covers 231,000 square inches, which is 1,604 sq ft.
Coverage in sq ft per gal = 1,604 ÷ thickness in mils.
- 14 mils: 115 sq ft per gal. That is B-707.
- 17 mils: 94 sq ft per gal. That is P-409 Moisture Vapor Primer.
- 5 mils: 321 sq ft per gal. That is a topcoat at the thick end of its range.
The formula is exact for 100% solids products because nothing evaporates: wet film equals dry film. For water-based and solvent-based coatings the dry film is the wet film multiplied by the solids by volume; T-521 is 38% solids by volume, so a 5 mil wet coat dries to about 2 mils. The product pages quote those products in wet mils, so the formula still predicts how far a gallon spreads. See what 100% solids epoxy means.
Coverage of every coating at its recommended thickness
| Product | Thickness | Coverage per gal | One kit covers |
|---|---|---|---|
| B-707 High Build Epoxy and B-181 | about 14 mils | about 115 sq ft | 0.75 gal: 85 sq ft. 1.5 gal: 175. 3 gal: 350 (one bay). 15 gal: 1,750 |
| B-933 Fast Cure Polyurea | 8 to 16 mils | 100 to 200 sq ft | 2.5 gal: one bay under flake |
| B-253 Novolac Seal | 16 mils | about 100 sq ft | 3 gal: about 300 sq ft |
| P-707LVP / P-181LVP Epoxy Primer | 6 to 12 mils | 133 to 267 sq ft | 3 gal: a 2-car garage, about 600 sq ft |
| P-015 Water Based Epoxy Primer | 5 to 7 mils | 229 to 320 sq ft | 2 gal: 460 to 640 sq ft |
| P-409 Moisture Vapor Primer | 17 mils, one coat | about 94 sq ft | 1.5 gal: about 140 sq ft. 3 gal: about 280. A 2-car garage takes two 3 gal kits |
| P-820 Oil Stop Primer | 5 to 8 mils wet | 200 to 320 sq ft | 2 gal: 400 to 640 sq ft or many spot repairs |
| P-139 Flexible Broadcast Primer | 20 mils | about 80 sq ft | 2 gal: one bay |
| P-257 Novolac Primer | 5 mils | about 320 sq ft | 3 gal: about 900 sq ft |
| C-671 Clear Epoxy | 16 to 18 mils | 90 to 100 sq ft | 3 gal: 270 to 300 sq ft, one metallic bay with 12 oz pigment |
| C-137MLV Chip and Quartz Binder | 12 to 18 mils | 90 to 133 sq ft | 3 gal: one bay |
| T-521 / T-520 Water Based Polyurethane | 3 to 5 mils wet | 320 to 500 sq ft | 1.5 gal: one bay. 3 gal: a 2-car garage |
| T-444X Polyaspartic | 5 to 12 mils wet | 133 to 320 sq ft | 2 gal: one bay of clear over flake |
| T-344 Polyaspartic, Fast Cure | 5 to 12 mils wet | 133 to 320 sq ft | 1.5 gal: one bay |
| T-322 / T-322S / T-321 / T-320 Solvent Urethane | 3 to 5 mils wet | 320 to 500 sq ft | 1.5 gal: one bay. 3 gal: 2-car. 15 gal: about 6,000 sq ft |
| T-359 High Wear Urethane | rolled thin | about 600 sq ft per gal kit (660 tinted) | 1 gal: 600. 4 gal: 2,400 |
| U-903SL / U-903M / U-903TC Urethane Cement | 1/8 in / 1/4 in / over sand | 37 to 46 / 23 / 160 to 170 sq ft per unit | one unit |
| A-Chips Decorative Flake, 1/4 inch | full broadcast | about 40 lb per 350 sq ft | 40 lb box: one bay. Light accent: 1 to 5 lb per bay |
| R-818 Epoxy Crack Filler | 1/8 by 1/8 inch crack | about 1,228 lineal ft per gal | 1 gal kit: a typical 2-car garage |
| R-830 Flexible Joint Sealant | 1/2 by 1/2 inch joint | 11 to 12 lineal ft per tube set | 2-car garage, two joints: 4 tube sets |
| R-110 Epoxy Mortar | 1/8 to 1/4 inch | Unit: 21.5 sq ft at 1/4 inch, 43 at 1/8 |
Every figure assumes the recommended thickness on a properly profiled slab. Prices and specs as of November 2026.
Three adjustments before you order
- Porous or rough concrete. A heavily ground, pitted or never-sealed slab soaks up the first coat. Rough or porous concrete uses more, so order the next size up when the floor is near the top of a range. On a very porous slab a thin primer coat of P-015 or C-137MLV costs less than a second coat of B-707; the B-707 data sheet notes that without a primer, more porous substrates may cause outgassing.
- Waste. Mixed epoxy left in the bucket, on the roller and in the squeegee is gone. Budget 10% on top of calculated gallons when buying components; kits carry that margin.
- Running out. Stopping mid-floor means a visible line and a sanding step. When your measurement lands within 10% of a kit's limit, buy the next size.
Flake and the topcoat over it
A full flake floor takes about 40 lb of 1/4 inch flake per car bay, broadcast into the wet base coat until the color disappears. The 40 lb box is $289.99 alone and is in every Full Flake kit.
- Smooth solid-color floor: T-521 at 3 to 5 mils wet, 320 to 500 sq ft per gal. One 1.5 gal kit per bay.
- Full flake floor: T-444X at 5 to 12 mils wet, 133 to 320 sq ft per gal. One 2 gal kit per bay. Over 12 mils wet, T-444X bubbles.
- Metallic floor: P-015 Black 2 gal kit as the ground coat, then C-671 at 16 to 18 mils with 12 oz of pigment per 3 gal kit, then T-521 at 3 to 5 mils. One 3 gal kit of C-671 covers 270 to 300 sq ft at 16 to 18 mils, or a full 350 sq ft bay at about 14 mils.
Worked examples
| Floor | Kit | What ships | Price |
|---|---|---|---|
| 1-car, 12 by 22 ft (264 sq ft) | Garage Pro 1-Car, solid | 1 x B-707 3 gal, 1 x T-521 1.5 gal, tool kit | $702.99 ($2.01/sq ft at 350) |
| Garage Pro 1-Car, full flake | 1 x B-707 3 gal, 1 x 40 lb flake, 1 x T-444X 2 gal, tool kit | $1,036.99 | |
| Garage Starter 1-Car, base coat only | 1 x B-707 3 gal, wand, squeegee | $350.99 | |
| 2-car, 20 by 22 ft (440 sq ft; over one kit's 350) | Garage Pro 2-Car, solid | 2 x B-707 3 gal (700 sq ft), 1 x T-521 3 gal, tool kit | $1,270.99 ($1.82/sq ft at 700) |
| Garage Pro 2-Car, full flake | 2 x B-707, 2 x 40 lb flake, 2 x T-444X 2 gal, tool kit | $1,961.99 | |
| Garage One-Day 2-Car, full flake | 2 x B-933 2.5 gal, 2 x 40 lb flake, 2 x T-444X 2 gal, tool kit | $1,709.99 | |
| 3-car, 30 by 30 ft (900 sq ft) | Garage Pro 3-Car, solid | 3 x B-707 3 gal (1,050 sq ft), T-521 3 gal + 1.5 gal, tool kit | $1,862.99 ($1.77/sq ft at 1,050) |
| Garage Pro 3-Car, full flake | 3 x B-707, 3 x 40 lb flake, 3 x T-444X 2 gal, tool kit | $2,887.99 | |
| Damp slab: add P-409 | 4 x 3 gal kits, about 1,120 sq ft at 17 mils | 4 x $389.99 | |
| 2,000 sq ft shop | Commercial Pro 2,000, solid | B-707 15 gal + 3 gal (18 gal, 2,070 sq ft at 115), 2 x T-322 3 gal + 1.5 gal (7.5 gal at 320 to 500 sq ft/gal), tool kit | $2,831.99 ($1.42/sq ft) |
| Commercial Pro 2,000, full flake | Same B-707, 6 x 40 lb flake, T-444X 10 gal + 2 gal, tool kit | $5,487.99 ($2.74/sq ft) |
A 24 by 24 ft garage at 576 sq ft is the same order as the 440 sq ft one. On the shop floor add R-830 for the saw-cut joints at 11 to 12 lineal ft per tube set. T-322 cannot ship to CA, DE or MD; we swap a compliant topcoat by phone after you order. Cost per square foot with prep and labor lines: materials cost per square foot.
Common questions
How much epoxy do I need for a 2-car garage?
Two 3 gal kits of B-707 for up to 700 sq ft at about 14 mils, plus one 3 gal kit of T-521. That is the 2-car Garage Pro System at $1,270.99. Full flake adds two 40 lb boxes of flake and two 2 gal kits of T-444X, $1,961.99.
How many square feet does a gallon of epoxy cover?
A gallon of 100% solids epoxy covers 1,604 sq ft at 1 mil, about 115 sq ft at 14 mils. Water-based coatings quote higher numbers because they go on thinner and shrink as the water leaves.
How much flake do I need for a garage floor?
About 40 lb per car bay, 350 sq ft, for a full broadcast. A light accent takes 1 to 5 lb per bay.
Enter your measurements in the epoxy calculator for the kit size, or assemble components in the kit builder. Questions on a rough or damp slab: (877) 703-7699, Monday to Saturday, 8am to 6pm ET.
