Regional costs
In estimating the cost of a paint job or comparing the cost of one paint to that of another, factors other than the cost per gallon must be taken into consideration. These additional factors include coverage rates, material cost per square foot, cost of surface preparation and application, expected service life, and cost of money.
As a rule of thumb...
Only 20-25 percent of the cost of painting is due to materials, the balance going for surface preparation and application.
It assumes the average door is 21 square feet in surface and the average window is 16 square feet.
It assumes that application paint goes on at about 350 square feet per gallon and 330 square feet for base paint.
It also assumes walls are smooth.
It takes into consideration spraying of the base coat, which takes slightly more paint than the alternatives, brushing or rolling, either of which requires roughly the same quantity of paint but less than spraying.
Prices include standard contractor grade materials and all related caulking and puttying.
Prices apply to only commercial applications and efficient scheduling.