How much epoxy do you need?

How much epoxy do I need for a garage floor?

Multiply the area by the number of coats and divide by the coverage per gallon. A gallon spread 1 mil thick covers 1,604 square feet, so a 100% solids epoxy at 10 mils covers 160 square feet per gallon. A 400 square foot floor with two coats needs 800 ÷ 160.4 = 5 gallons, before any extra.

How much epoxy resin do I need for a table or river pour?

Multiply length × width × depth in inches and divide by 231, the cubic inches in a gallon. A 48 × 24 inch pour 1 inch deep is 1,152 cubic inches, or 4.99 gallons (18.9 liters). For a river table, measure only the gap the resin fills.

What does percent solids mean?

It is the share of the coating that stays on the floor after the water or solvent evaporates. A 100% solids epoxy dries as thick as it goes on; a 50% solids product leaves half the film, so the same gallon covers half the area at the same dry thickness — 80 instead of 160 square feet at 10 mils.

What is a mil?

A mil is one thousandth of an inch, or 25.4 micrometers. Epoxy floor coatings are usually specified as a dry film thickness in mils on the data sheet, often per coat.

Should I buy extra epoxy?

Yes — some always stays in the mixing bucket and roller, and a rough or porous floor soaks up more. The calculator adds 10% by default; raise it for bare, porous concrete, and check the coverage on your product's data sheet.

Is the thickness per coat or the total?

The calculator treats the thickness you enter as the thickness of each coat and multiplies the quantity by the number of coats. For a 440 square foot floor at 10 mils, one coat of a 100% solids epoxy needs 2.7 gallons and two coats 5.5. Check the data sheet: some products specify a total build, and others a thickness per coat.

How deep can I pour epoxy resin in one layer?

Deep-pour and table-top resins have different maximum layer depths, set by how much heat the curing resin makes. A resin poured too deep in one go can overheat, yellow or crack. The maximum depth per pour is on the manufacturer's data sheet; where a pour is deeper than that, it is done in several layers, and the volume is the sum of the layers.

The coverage formula

A US gallon is 231 cubic inches. Spread one mil (0.001 inch) thick, it covers 231 ÷ 0.001 = 231,000 square inches, which is 231,000 ÷ 144 = 1,604 square feet. So the coverage per gallon is 1,604 × solids fraction ÷ thickness in mils. Gallons needed equal area × coats ÷ coverage per gallon. For a pour, the volume is length × width × depth in cubic inches divided by 231. The solids fraction accounts for products that lose volume as solvent or water evaporates.

Worked example: a 440 square foot garage floor and a 60 inch table

At 10 mils a gallon of 100% solids epoxy covers 160.4 square feet, so one coat on 440 square feet is 2.74 gallons and two coats 5.49. A 50% solids product covers 80.2 square feet per gallon and needs 5.49 gallons for one coat. A thinner 6 mil coat of the 100% solids product takes 1.65 gallons. A river-table pour 60 inches long, 20 inches wide and 1.5 inches deep is 1,800 cubic inches, or 7.79 gallons (29.5 liters).

Common mistakes

Using the wet-film thickness where the data sheet means the dry-film thickness is the first mistake, and it matters most for products that are not 100% solids. The second is forgetting how porous concrete soaks up the first coat; bare, porous slabs often need a primer coat or extra material. The third is mixing more than can be used in the working time, since mixed epoxy cures in the pail. For pours, forgetting that the mold and any objects in it displace resin makes the estimate too high, while forgetting leaks and the resin that stays in the mixing container makes it too low; mix a little extra.

Sources: coverage of 1,604 square feet per gallon at 1 mil is derived from the definition of the US gallon (231 cubic inches, NIST SP 811) and the mil (0.001 inch); layer and cure limits are set by the product's data sheet, which prevails over this page. Related: concrete calculator, paint calculator, square footage calculator and tank volume calculator.