Average coverage for paint is approx 400 square feet per gallon. This applies to most spray, roll-on or brushed on coatings. To figure out coverage for the product you're interested in, divide the number of ounces of product by 128, then multiply by 400.
E.g. From a 12oz can of VHT Paint, you can expect to cover 37.5 sq ft.
(12/128 = 0.09375 * 400 = 37.5)