Paint a Room: Calculators in Order

Paint quantity is an area problem, and area is easy to get wrong in both directions: forget the ceiling and you run short, forget the doors and windows and you buy a gallon you do not need. Take the measurements once and let the calculators carry them through.

Take a 12 x 14 ft room with 8 ft walls. The perimeter is 52 ft, so the walls are 416 sq ft. A door of about 20 sq ft and a window of about 15 sq ft come off, leaving about 381 sq ft. Two coats double that to 762 sq ft, and at a coverage of roughly 350 sq ft per gallon it needs 2.2 gallons, so you buy three. Use the coverage printed on your can, because it changes with the product and the surface.

Prep decides how the paint looks. Patch nail holes and dings with lightweight spackle, and for larger repairs use joint compound and calculate how much you need. Sand, wipe off the dust, and prime any patch or dark color that you are covering, because primer costs less than a third coat.

Trim is a separate line: baseboards, casings and doors need linear feet of trim paint and often a different sheen. Ceilings take a flat finish and are usually painted first. Finish with a cost check if you are hiring the job, and add the paint and supply lists to your project list.