Coverage (sq ft/gal) = 1,604 × volume solids ÷ mils. A gallon spread 1 mil thick covers 1,604 sq ft. At 10 mils of 100%-solids epoxy that is ~160 sq ft/gal; a water-based (≈50% solids) kit covers ~80 sq ft/gal at the same dry thickness.
A 24×24 ft (576 sq ft) garage at 10 mils of 100%-solids epoxy, 2 coats, needs about 7.2 gallons, roughly 8.3 with 15% for porous concrete.
The share of the liquid that stays as a hard film. Water- or solvent-based kits lose part of it to evaporation, so they cover less at the same dry thickness.
Bare concrete soaks up epoxy. Primers and first coats often cover 20–30% less than the chart says.
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