Paint Calculator

A 12x12 room with 8-ft ceilings, one door, and one window needs about 1.5 gallons for one coat or 3 gallons for two coats, including ceiling paint if desired.

One gallon of interior paint typically covers 350-400 square feet. Higher quality paints often have better coverage. Dark colors and textured surfaces may need more paint.

Primer is recommended when painting over dark colors, new drywall, or stained surfaces. For most repaints of similar colors, two coats of paint without primer is sufficient.

To paint a room, start by clearing the area and cleaning the walls with mild soap. Tape off trim, baseboards, and window frames using painter's tape. Lay down drop cloths. Begin by 'cutting in' the corners and edges with a 2-inch angled brush. Then, use a roller in a 'W' or 'N' pattern to fill the walls, working in 3-by-3 foot sections. For a professional finish, apply two coats of premium paint, allowing at least 2 to 4 hours of drying time between applications.

To find exactly how much paint you need, use our free online Paint Calculator. Measure the length, width, and wall height of your room. Multiply the room perimeter by the height to find the gross wall area, and then subtract 21 square feet per door and 15 square feet per window. Divide the final net wall area by the coverage rate of your paint (typically 350 to 400 square feet per gallon) and multiply by the number of coats (we recommend two coats for durability).

Generally, standard interior or exterior repainting of an existing house is considered routine maintenance rather than a capital improvement by the IRS. However, if the painting is part of a larger, comprehensive home renovation project (such as adding an extension or rebuilding a kitchen), the painting cost can be capitalized as part of the overall improvement. Capital improvements increase your home's cost basis, which can reduce tax liability when selling the property.