How much epoxy per square foot?
A gallon of liquid spread one mil (a thousandth of an inch) thick covers 1,604 sq ft. Divide by the wet thickness and multiply by the solids content to get real coverage: 100% solids epoxy at 10 mils covers about 160 sq ft per gallon, while a 50%-solids water-based kit at 6 mils covers about 134 sq ft per coat — but leaves only half that thickness once the water evaporates.
Example: a 20' x 20' two-car garage (400 sq ft) with one 10-mil coat of 100% solids epoxy needs about 2.7 gallons with 10% extra for porous concrete.
Flakes
Decorative vinyl flakes are scattered into the wet base coat. A light sprinkle takes about 1 lb per 250 sq ft. A full broadcast, thrown until the base won't take any more, takes roughly 1 lb per 8–10 sq ft — about 44 lb for a 400 sq ft garage — and should get two clear topcoats.
Preparation matters most
Coatings fail when they don't bond. Grind or etch the concrete, clean off all oil, fill cracks, and check for moisture: tape a square of plastic to the slab overnight, and if it's damp underneath, the floor isn't ready.
Pouring a new slab first? Use the concrete calculator.