How much white paint is needed to paint a 1000 square foot building?

1000 square feet to paint? You can paint 400 feet squared with one gallon. so you need to know how high the wall is 8 feet high by 1000 feet 8x1000 = 8000 square feet divided by 400feet per a gallon = 20 gallons one coat. just x the amount of coats you want to do and your good to go. You realy need to measure each wall and go HxL divided by 400feet per a gallon and this will tell you how many gallons will be needed to paint each wall and corner.