Ordering the right amount of material is one of the first questions every homeowner asks, and the math is simpler than you'd think. Here's how to figure out exactly what you need — and why ordering a little extra is always the right call.
The basic formula
Square footage ÷ coverage rate = gallons needed
That's it. The coverage rate is on the Technical Data Sheet (TDS) for every product. Here's what our products cover:
- Polyaspartic (RS-POLY-90): 300 to 400 SF per 2 gal kit
- 100% Solids Epoxy (RS-EP-100): 300 to 400 SF per 3 gal kit
- MVB Primer (RS-MVB): about 300 SF per 2 gal kit
- Decorative flake (RS-FLK): about 350 SF per 40 lb box at full broadcast, 700 SF at partial
Notice the coatings give a range, not a single number, and that range is the most useful thing on this page. A kit holds a fixed amount of material, so how far you spread it decides how thick it lands — coverage and film thickness are the same dial read from opposite ends.
- Spread a kit to 400 SF and you land at the low end of the recommended film thickness. Economical, in spec, and what the numbers below assume.
- Hold it to 300 SF and you land at the high end — same money, less floor, a thicker coating.
Pick 300 SF per kit if the slab is rough or porous, or the floor is going to work for a living. Pick 400 for a sound residential garage. What you can't do is stretch past 400: below-spec film is where cratering, skid marks, and early wear-through come from.
Step 1: Measure your floor
Measure length and width in feet. Multiply them together for square footage.
A standard two-car garage is roughly 20 ft x 20 ft = 400 square feet. A three-car garage is typically 30 ft x 20 ft = 600 square feet.
If your space isn't a perfect rectangle, break it into rectangles, calculate each one, and add them up. Don't forget to subtract any areas you won't be coating (raised platforms, built-in workbenches, etc.).
Step 2: Calculate gallons
Let's say you're doing a two-car garage (400 SF) with the double polyaspartic system (two coats of polyaspartic, no epoxy base):
First coat (polyaspartic): 400 SF ÷ 400 SF/kit = 1 kit Second coat (polyaspartic): 400 SF ÷ 400 SF/kit = 1 kit Total polyaspartic needed: 2 kits (4 gallons total)
That lands exactly on the boundary — 400 SF is precisely one kit per coat at the economical spread, with no slack. Read the next section before you order, because this is the size where the waste factor stops being optional.
Hold the same two kits to 300 SF per coat instead and you'd coat a 300 SF space at the thick end of the range for the identical money.
Step 3: Add a waste factor
Real floors aren't laboratory conditions. You'll lose material to:
- Mixing containers (a thin film always sticks to the bucket)
- Squeegee and roller absorption
- Edges and corners that need extra attention
- Uneven concrete that soaks up more material in low spots
Add 10–15% to your calculated amount. This is not optional — it's the difference between having enough material to finish the job and running out 30 square feet from the end with no way to match the batch.
In practice, kits only come in whole kits, so the waste factor turns into a simple rule: if your floor lands within about 10% of a kit boundary, buy the next kit. A 400 SF garage divides into exactly one kit per coat with nothing to spare, so a slab that drinks more than expected leaves you short. At 380 or 400 SF, order two. At 250, one is genuinely fine.
Common project sizes
Here are quick references for the most common residential jobs:
Two-car garage (400 SF) — Double Poly System:
- 2 kits RS-POLY-90 (4 gal total, 1 kit per coat)
- Flake, if full broadcast: 2 boxes (80 lb — the box threshold is 350 SF, so 400 needs a second one)
- Add MVB primer if needed: 2 kits
Two-car garage (400 SF) — Full Flake System:
- 1 kit RS-EP-100 base coat, plus a pigment pack if you're coloring it
- 1 kit RS-POLY-90 topcoat
- Flake: 2 boxes (80 lb) at full broadcast, 1 box at partial
- Add MVB primer if needed: 2 kits
Three-car garage (600 SF) — Double Poly System:
- 4 kits RS-POLY-90 (2 per coat)
- Flake, if full broadcast: 2 boxes (80 lb)
- Add MVB primer if needed: 2 kits
Basement or shop (800 SF) — Double Poly System:
- 4 kits RS-POLY-90 (2 per coat — 800 divides evenly, so no slack; consider a fifth)
- Add MVB primer if needed: 3 kits
What happens if I run out mid-coat?
This is the scenario you want to avoid. If you run out of material halfway through a coat, you'll have a visible line where the wet edge dried before you could continue. This is called a "cold joint" and it's very difficult to fix. The only real fix is to sand the entire floor and start the coat over.
Always order at least one extra kit beyond your calculation. Unopened kits can be returned or saved for a future project. Running out mid-pour cannot be undone.
What about thickness?
The mil thickness is how thick the cured coating is, measured in thousandths of an inch. 8 mil = 0.008 inches.
Going thicker uses more material but gives you a more durable, longer-lasting floor. Going thinner stretches material but risks an under-built floor that wears through in high-traffic areas.
Stick to the recommended thickness — and note these ranges are the same information as the coverage ranges above, just measured the other way:
- Polyaspartic: 8–12 mil per coat (400 SF/kit gets you the 8, 300 SF/kit gets you the 12)
- Epoxy: 5–8 mil per coat (same idea — 400 SF/kit is the thin end)
- Primer: 6–8 mil
Don't try to save money by going thin. The material cost difference between 8 mil and 6 mil is maybe $30, but the durability difference is years of lifespan.
The bottom line
Measure your space, divide by 400 for the economical spread (or 300 if you want the thicker film), add 10–15%, and round up to the nearest kit. When in doubt, order one extra kit. It's cheaper than redoing a floor because you ran short.
Or skip the arithmetic: the wizard on any system page sizes every layer from your square footage and prices the whole kit.