Work out how many gallons of epoxy you need for a garage or basement floor coating, or for a resin pour on a tabletop, bar top or river table. For a pour it also splits the total into resin and hardener.
How to use the epoxy calculator
- Choose Floor coating for a painted-on coat measured in mils, or Resin pour for a layer measured in inches.
- Enter the size of the floor or the surface. For a table, measure only the area the resin will cover.
- Floor coating: enter the dry film thickness per coat, the number of coats and the volume solids from the product data sheet.
- Resin pour: enter the depth and the mix ratio on the kit. Add the maximum depth per pour from the label to see how many pours it takes.
- Keep 10% extra for what stays in cups, rollers and porous concrete.
Epoxy formulas
Coverage (ft² per gallon) = 1,604 × volume solids ÷ dry mils Gallons for a floor = area (ft²) × coats ÷ coverage Resin volume (in³) = length (in) × width (in) × depth (in) Gallons for a pour = cubic inches ÷ 231 Part A = total × A ÷ (A + B), Part B = total × B ÷ (A + B)
A US gallon is exactly 231 cubic inches. Spread at 1 mil (0.001 in) it covers 231,000 in², which is 1,604 ft². That is the factor in Spartan Chemical’s coverage formula: divide it by the thickness in mils and multiply by the volume solids. Solvent-free epoxy is 100% solids, so what you roll on stays on. In a water-based or solvent-based product part of the film evaporates, so the same gallon builds a thinner dry coat.
Worked example: a two-car garage floor
- Area: 20 × 20 = 400 ft².
- Coverage at 10 dry mils, 100% solids: 1,604 ÷ 10 = 160 ft² per gallon per coat.
- Two coats: 400 × 2 ÷ 160.4 = 4.99 gallons.
- With 10% extra: 5.49 gallons, so 6 one-gallon kits.
The same floor with a 50% solids product at 10 dry mils per coat takes twice as much: each gallon covers only 80 ft².
Worked example: a tabletop flood coat
- Volume: 72 × 36 × 1/8 = 324 in³.
- Gallons: 324 ÷ 231 = 1.4 gal, or 1.54 gal (197 fl oz) with 10% extra.
- A 1:1 kit splits that into 0.77 gal of resin and 0.77 gal of hardener.
A river table with a 6 in wide river down a 72 in slab, 1.5 in deep, holds 648 in³, about 2.81 gallons before extra. If the label allows 1/2 in per pour, that is three pours.
Epoxy coverage per gallon
Square feet per gallon per coat at common dry film thicknesses:
| Dry film per coat | 100% solids | 50% solids |
|---|---|---|
| 3 mils | 535 ft² | 267 ft² |
| 5 mils | 321 ft² | 160 ft² |
| 8 mils | 201 ft² | 100 ft² |
| 10 mils | 160 ft² | 80 ft² |
| 12 mils | 134 ft² | 67 ft² |
| 15 mils | 107 ft² | 53 ft² |
| 20 mils | 80 ft² | 40 ft² |
Duraamen’s coverage chart works the same examples: 160 ft² per gallon at 10 mils for a 100% solids coating and 80 ft² for a 50% solids one. Bare concrete soaks up some of the first coat, so primers and first coats often cover less than the chart says.
Resin per square foot
How much resin one square foot takes at each pour depth:
| Pour depth | Cubic inches | Fluid ounces | Gallons |
|---|---|---|---|
| 1/16 in | 9 in³ | 5 fl oz | 0.039 gal |
| 1/8 in | 18 in³ | 10 fl oz | 0.078 gal |
| 1/4 in | 36 in³ | 19.9 fl oz | 0.156 gal |
| 1/2 in | 72 in³ | 39.9 fl oz | 0.312 gal |
| 1 in | 144 in³ | 79.8 fl oz | 0.623 gal |
| 2 in | 288 in³ | 159.6 fl oz | 1.247 gal |
Floor coating or resin pour?
Floor epoxy goes on thin, a few mils to a few dozen mils per coat, and is sold by coverage. Table-top and casting resins go on in layers measured in fractions of an inch. Deep-pour resins can go thicker in one pour because they cure slowly; table-top resins can overheat, yellow or crack if they are poured too deep at once. Always follow the depth limit on the label.
Tips for epoxy projects
- Read the data sheet. It gives the volume solids, the coverage and the thickness per coat. Those numbers beat any rule of thumb.
- Mix full kits. Epoxy cures by chemistry, so the ratio matters. Mix whole kits, or measure parts exactly when you split one.
- Measure by the right unit. A ratio given by weight is not the same as one given by volume.
- Seal the wood first. Bare wood releases air into a pour. A thin seal coat stops the bubbles and uses a little extra resin.
Questions
How much epoxy do I need for a two-car garage?
About 5.5 gallons for a 20 × 20 ft floor with two coats at 10 dry mils of 100% solids epoxy, including 10% extra.
How many square feet does a gallon of epoxy cover?
1,604 ÷ the dry mils × the volume solids. A 100% solids epoxy covers about 160 ft² at 10 mils and 321 ft² at 5 mils.
How much resin do I need for a 4 × 8 ft table?
At 1/8 in deep: 48 × 96 × 0.125 = 576 in³, or 2.49 gallons, before extra.
How many mils are in an inch?
1,000. A mil is a thousandth of an inch, so 10 mils is 0.01 in.
Sources
- Concrete Evidence Info/Tech Bulletin: Mil Thickness, Spartan Chemical Company.
Used for: Coverage = solids × 1,604 ÷ mils, and where the 1,604 factor comes from. - Coatings Coverage Chart, Duraamen Engineered Products.
Used for: Coverage examples at 100% and 50% solids. - NIST Guide to the SI, Appendix B.8: Factors for units listed alphabetically, National Institute of Standards and Technology.
Used for: 1 US gallon = 231 in³ and 3.785411784 L; inch and foot definitions.