Resin floors are priced by thickness, so the quantity of epoxy you need comes from two numbers: the floor area and the thickness you are applying. Everything else is waste, primer and rounding up to whole kits.
This guide gives you the basic rule in metric and imperial, a coverage table, and two worked examples. The coverage rate on the product data sheet always overrides a general rule, so use these figures to check an estimate, not to replace the data sheet.
The basic rule
One square metre covered to a thickness of one millimetre is one litre of material.
Mass (kg) = volume × mixed density (kg/L) × (1 + waste %)
Kits = round up (mass ÷ kit size)
In US units, one US gallon covers about 1,604 ft² at a thickness of one mil (0.001 inch). Divide 1,604 by the thickness in mils to get coverage per gallon.
Coverage table
These figures are theoretical coverage for a 100% solids system with no waste. Solvent-based and water-based coatings lose volume as they dry, so use the data sheet for those.
| Thickness | Metric coverage | Coverage per 20 L | US coverage per gallon (approx.) |
|---|---|---|---|
| 0.25 mm (10 mil) | 4 m² per litre | 80 m² | 160 ft² |
| 0.5 mm (20 mil) | 2 m² per litre | 40 m² | 80 ft² |
| 1 mm (40 mil) | 1 m² per litre | 20 m² | 40 ft² |
| 1.6 mm (about 1/16 in) | 0.63 m² per litre | 12.5 m² | 25.7 ft² |
| 2 mm | 0.5 m² per litre | 10 m² | 20 ft² |
| 3 mm (about 1/8 in) | 0.33 m² per litre | 6.7 m² | 13 ft² |
| 5 mm | 0.2 m² per litre | 4 m² | 8 ft² |
Worked example 1: garage floor in square feet
A 500 ft² garage with a roller-applied coat at 20 mil.
- Coverage at 20 mil is about 80 ft² per gallon.
- 500 ÷ 80 = 6.25 gallons.
- Add 10% waste: 6.25 × 1.10 = 6.9 gallons, so order 7 gallons (or the next kit size up).
The primer is separate. Calculate it from its own coverage rate in ft² per gallon.
Worked example 2: warehouse floor in metric
A 200 m² floor with a 2 mm self-smoothing system, mixed density 1.6 kg/L, in 20 kg kits.
- Volume: 200 × 2 = 400 L.
- Mass: 400 × 1.6 = 640 kg.
- Add 10% waste: 640 × 1.10 = 704 kg.
- Kits: 704 ÷ 20 = 35.2, so order 36 kits.
Mixed density and waste
Mixed density is on the technical data sheet. Unfilled clear epoxy sits near 1.1 kg/L. Self-smoothing systems with filler are usually 1.4 to 1.7 kg/L. Heavy-duty screeds run higher.
Waste covers mixing pots, edges, rollers and the surface profile soaking up material. 10% suits most jobs. Use 15% on rough, shot-blasted or open-textured slabs.
What the quantity does not include
- Primer. It soaks into the concrete and is calculated separately.
- Broadcast aggregate or flake. Calculate it from the system data sheet.
- Topcoats and sealers. Each coat has its own coverage rate.
- Extra thickness on uneven floors. The floor fills low spots before it reaches your design thickness, so add 5 to 10% thickness on uneven slabs.
Frequently asked questions
How much epoxy do I need per square foot?
It depends on thickness. At 20 mil, one US gallon covers about 80 ft², which is roughly 0.0125 gallons per ft². At 40 mil it is about 40 ft² per gallon.
How much epoxy do I need per square metre?
One litre per m² for every millimetre of thickness. A 2 mm system needs about 2 litres per m², or about 3.2 kg per m² at a density of 1.6 kg/L, before waste.
Does the stated coverage on the can include waste?
Usually not. Coverage figures are theoretical, so add waste for the mixing, edges and surface profile.
Do I include primer in the thickness?
No. Primer soaks into the concrete and is calculated from its own coverage rate.
Can I rely on this for a quote?
Use it to check your estimate. Take final quantities from the data sheet for the exact product, and confirm kit sizes and densities with the supplier.
Figures are theoretical coverage for guidance. The manufacturer's data sheet decides the coverage, density and application thickness for the product you are installing.