Epoxy Garage Floor Coating Calculator

A 2-car garage is typically about 400 sq ft (20x20 ft). With 100 percent solids epoxy at the standard 1/8 in (125 mils) thickness: 400 x 125 / 1604 = 31.2 gallons. With water-based epoxy paint at about 250 sq ft per gallon per coat: 400 / 250 = 1.6 gallons per coat, so 3.2 gallons for two coats plus primer. As a sanity anchor, Angi's published table lists 18.7 gallons for a 12x20 ft garage (240 sq ft) at 1/8 in - the same formula gives 240 x 125 / 1604 = 18.70 gallons.

Gallons = square feet x thickness in mils / 1604. In inches: sq ft x inches x 144 / 231. Example: 240 sq ft at 125 mils (1/8 in) -> 240 x 125 / 1604 = 18.7 gallons. The constant 1604 is the square footage one gallon covers at 1 mil thickness (100 percent solids): 231 cubic inches per gallon x 1000 / 144. Lower-solids products need proportionally more material, which is why the System tab works from per-product coverage instead.

Epoxy primer typically covers 150 to 200 sq ft per gallon on bare concrete (a 3-gallon 100 percent solids primer kit covers 480 to 600 sq ft at 8 to 10 mils, per manufacturer data). This calculator defaults to 175 sq ft per gallon. Example: 240 sq ft / 175 = 1.37 gallons, so buy 2 gallons. Skip primer only on previously coated, sound floors - and even then a recoat primer is cheap insurance.

Water-based epoxy paint covers about 250 sq ft per gallon per coat and leaves 2 to 3 mils of dry film per coat - cheap and easy for DIY, but thin. 100 percent solids epoxy covers about 150 sq ft per gallon and leaves 10 or more mils per coat, with much better abrasion and hot-tire resistance. Solvent-based sits in the middle at roughly 200 sq ft per gallon. For a working garage that sees cars daily, 100 percent solids with a polyaspartic topcoat is the durable choice; water-based is fine for light-duty storage garages.

For 1/4 in vinyl flake, full broadcast coverage needs 5 to 7 sq ft per pound (Epoxy FX published rate); partial or light broadcast runs 25 to 250 sq ft per pound depending on the look. Example: 240 sq ft at full broadcast, 240 / 6 = 40 lb, so buy two 25-lb boxes. Flake is broadcast into the wet base coat, then locked in with the clear topcoat.

Part A = total x 2/3, part B = total x 1/3 (ratio by volume - always confirm on your label). A 3-gallon kit at 2:1 gives 2.0 gallons of part A and 1.0 gallon of part B. A 1.5-gallon batch at 2:1 gives 1.0 gallon of A and 0.5 gallon of B. At 1:1 it is simply half and half. The Kit Sizer tab does this for 1:1, 2:1, 3:1 and 4:1 ratios.

Example for a 12x20 ft garage (240 sq ft) at 1/8 in with 100 percent solids epoxy: 18.7 gallons x $100 per gallon = $1,870 plus about $120 of primer, roughly $1,990 in materials. A professional job at $7 per sq ft costs 240 x 7 = $1,680 for the same floor - pros can be cheaper on small garages because they buy material wholesale and work fast. Angi reports the average professional epoxy floor at $2,514. DIY wins on large floors; get quotes on small ones.

Thin paint-grade systems run 8 to 10 mils total. The residential standard is 1/8 in (125 mils) of 100 percent solids epoxy - about 18.7 gallons per 240 sq ft. Heavy-duty or commercial floors go 1/4 in (250 mils), doubling the material to about 37.4 gallons per 240 sq ft. The Thickness tab converts any custom mil thickness to gallons.

Most epoxy floor failures are adhesion failures, and almost all of them trace back to prep: oil contamination, moisture vapor, or coating over smooth steel-troweled concrete with no profile. Diamond grinding is the reliable prep (etching is the budget fallback). Degrease oil stains, repair cracks, and do the plastic-sheet moisture test - tape down 2x2 ft of plastic for 24 hours; if the concrete underneath is damp, do not coat. Good prep is the difference between a 15-year floor and peeling in one summer.

Only if the existing coating is sound and well bonded - scrape-test it first, and anything peeling or loose must come off. Scuff-sand to dull the gloss, clean thoroughly, and use a recoat primer (about 400 sq ft per gallon for recoat-primer products) before the epoxy. Never coat over a failing floor hoping the epoxy will glue it down - it will not.

Always follow your product's label - cure times vary by chemistry and temperature. Typical guidance: light foot traffic after 24 hours, and wait 5 to 7 days before parking vehicles on 100 percent solids systems. Apply between roughly 50 and 90 F with low humidity; cold or damp concrete slows the cure dramatically. Hot-tire pickup resistance keeps improving for weeks after the floor feels hard.

No. This tool sizes FLOOR COATING - garage, basement and workshop floors in square feet, gallons per coat, flake and kits. If you are coating a table top, filling a river table channel, or casting a mold with epoxy resin, use our epoxy resin calculator instead, which works in cubic inches and mix ratios for casting. Different product, different math, different tool.