How to use the epoxy floor calculator
Epoxy is sold by the gallon or litre but specified by the thickness of the dry film left on the floor. This calculator turns the floor area and the thickness of each coat into the volume to buy, so you can compare quotes, check that a kit is enough, or budget a garage, workshop, showroom or basement floor before you order.
- Enter the floor area as length × width, or type a known area. For L-shaped rooms, add the rectangles together.
- Pick a system or choose Custom. The presets are typical values, not any brand's data sheet.
- Set each coat's dry film thickness and volume solids. Leave a coat at 0 to drop it.
- Add waste: about 10% for smooth sealed concrete, more for rough or porous slabs.
- Enter your kit size and price to see how many kits to buy.
Epoxy coverage formula
1 US gal = 231 in³ → covers 1,604 ft² at 1 mil dry (231 ÷ 0.001 ÷ 144)
US: gal per coat = area (ft²) × DFT (mils) ÷ (1,604 × solids)
Metric: litres per coat = area (m²) × DFT (µm) ÷ 1,000 ÷ solids
Order = Σ coats × (1 + waste) · kits = ⌈order ÷ kit size⌉
DFT is dry film thickness and solids is the fraction of the liquid left after curing, as a decimal. The table converts common thicknesses for 100% solids product.
| Dry thickness | Coverage per US gal | Coverage per litre |
|---|---|---|
| 5 mils (127 µm) | 321 ft² | 7.9 m² |
| 10 mils (254 µm) | 160 ft² | 3.9 m² |
| 20 mils (508 µm) | 80 ft² | 2.0 m² |
| 1/16 in = 62.5 mils (1.6 mm) | 26 ft² | 0.63 m² |
These are theoretical figures. Real spread rates are lower on rough concrete, so always allow for waste and check the data sheet.
Worked examples
A two-car garage in US units
A 20 × 20 ft garage is 400 ft². A primer at 5 mils, a base coat at 10 mils and a clear topcoat at 4 mils, all 100% solids, need 400 × 5 ÷ 1,604 = 1.25 gal, 2.49 gal and 1.00 gal. The total is 4.74 gal, or 5.21 gal with 10% waste. With 3 gal kits, buy 2.
A water-based two-coat system
The same 400 ft² with two 3 mil coats at 40% solids needs 400 × 3 ÷ (1,604 × 0.4) = 1.87 gal per coat, or 3.74 gal total and 4.11 gal with waste. The low solids mean you apply far more wet product for a thin film.
A metric self-leveling floor
A 5 × 4 m workshop floor is 20 m². A 1.6 mm (1,600 µm) self-leveling coat at 100% solids is 20 × 1,600 ÷ 1,000 = 32 L, or 35.2 L with 10% waste.
Who this calculator helps
- Architects and interior designers specifying resinous floors for garages, studios, retail and light industrial space and checking contractor quantities.
- Flooring contractors and estimators pricing coatings and planning kit orders.
- Facility managers budgeting a warehouse or workshop refit.
- Homeowners deciding between a DIY kit and a professional install.
Practical tips
- Prep decides how long the coating lasts. Grind or blast the slab, repair cracks, and test moisture before you buy product. Quantify the slab itself with the square footage calculator, or the concrete calculator if you are pouring a new one.
- Compare resinous floors with tile using the tile calculator, and plan wall finishes above the floor with the paint calculator.
- Mix only what you can roll within the pot life, and respect the slab and air temperature range on the data sheet.
- Buy all the material for a room in one go from the same batch so colour matches.
Want to preview a polished or coated floor before committing? Try different finishes on a photo with AI Flooring.
