You're staring at a 1,500-square-foot basement and a data sheet that says "250 SF/gallon at 8 mil DFT." Question: how many gallons do you order?
The answer is not 1,500 ÷ 250 = 6 gallons. Or rather, that's the number on the data sheet. The number on the truck is bigger, for reasons that are obvious in retrospect and surprising in advance.
Here's the math.
The base formula
The data sheet gives you theoretical coverage — how far one gallon goes if every drop ends up on the floor at the spec'd dry-film thickness.
Theoretical gallons = floor area (SF) ÷ coverage rate (SF/gal)
For a 1,500 SF basement coated with our 90% Solids Polyaspartic at 8 mil DFT (250 SF/gal):
1,500 ÷ 250 = 6 gallons
That's the number you'd order if you were a robot in a clean room.
The waste factor
Every real job loses material to:
- Substrate texture. Rough concrete drinks more resin than smooth concrete. CSP 4 absorbs 10–15% more than CSP 2.
- Edges and corners. You can't squeegee a corner; you cut in with a brush, which leaves more film.
- Mix-bucket loss. A few ounces stay on the paddle and the bucket walls of every kit you mix.
- Re-rolling and back-passes. Self-leveling polyaspartic still needs back-rolling, which uses material.
- The gap between what you ordered and what you actually pour. Pot life is short; you'd rather have one extra kit than be 0.4 gallons short with 8 minutes left to mix.
A reasonable waste factor for residential work is 10%. For commercial work on textured slabs, 15%. For broadcast-flake systems, 20% because you're losing flake along with resin.
Real gallons = theoretical × (1 + waste%)
For our 1,500 SF basement at 10% waste:
6 × 1.10 = 6.6 gallons
You order in whole kits, so you round up to the next kit size: 7 gallons if you're buying singles, or two 4-gallon kits if that's the pack size.
A worked example: 400 SF garage, full system
This is the most common residential project. Here's the full math.
Assume:
- Floor area: 400 SF
- System: epoxy base coat + flake broadcast + polyaspartic topcoat
- Substrate: 5-year-old concrete, lightly etched (CSP 2)
- Slab is dry, no MVB primer needed
Base coat: 100% solids epoxy at 10 mil DFT, 160 SF/gal
400 ÷ 160 = 2.5 gal theoretical
2.5 × 1.10 = 2.75 gal with waste
Round up → 3 gallons (one 3-gal kit)
Topcoat: 90% solids polyaspartic at 8 mil DFT, 250 SF/gal
400 ÷ 250 = 1.6 gal theoretical
1.6 × 1.10 = 1.76 gal with waste
Round up → 1 × 2-gal polyaspartic kit (1:1 ratio · low odor)
Flake: Roughly 0.25 lb per SF for a half broadcast, 0.5 lb per SF for a full
400 × 0.25 = 100 lb half broadcast
400 × 0.50 = 200 lb full broadcast
Most homeowners pick a half broadcast for the "subtle confetti" look, full broadcast for the dense flake floor.
Total order for the garage:
- 1 × epoxy base-coat kit (sized to job — stocking soon)
- 1 × 2-gal polyaspartic kit (in stock today)
- 100 lb flake (half broadcast)
- Tools, tape, mixing buckets
When to round up further
Add another 5–10% on top of waste factor when:
- The slab is rougher than you planned for (CSP 4+)
- It's your first time pouring this system
- You're working in heat (you'll mix more, smaller batches)
- The shape of the floor has lots of edges relative to area (long thin hallway vs. open garage)
- You can't easily reorder if you run short — like a Saturday afternoon when your supplier closes at noon
When you can round down
Almost never. The cost of one extra kit is ~$150. The cost of being half a gallon short with 6 minutes of pot life left is a half-finished floor and a re-pour the following weekend. Round up.
Use the calculator
We built a coverage calculator that does this math for you. Pick a product, enter the floor area, set the waste factor, and it tells you how many kits to order.
Or, if you'd rather just describe the job, send us the dimensions and we'll quote the system. We deliver kits within our 200-mile zone — Austin to Houston, Dallas, San Antonio, and everything in between.