Agya wrote:how do we convert a gallon of premium latex paint is supposed to cover 400 square feet. How thick would the layer of paint be?
The conversion will be based on the fact that one gallon is 231 cubic inches.
To work the math we need to be in the same units, so we'll convert 400 square feet to square inches by multiplying by 144 (1 ft² = 1 ft · 1 ft = 12 in · 12 in = 144 in²)
So we have 231 cubic inches of paint, and we're going to spread it out over 57,600 square inches.
231 in³ / 57,600 in² = 0.004 in
So, While WET, the thickness of the paint will be four thousandth of an inch. (about 0.1 mm) It will be thinner when the water evaporates off.
Just a guess, but I doubt you'll be able to get 400 square feet of coverage out of a gallon of paint without a laboratory.