How Many Quarts of Paint to Cover Interior Walls?

Area Covered

• To estimate the amount of paint you need to paint the walls of a room, first calculate the approximate area of the walls. Measure and note the height and width of each wall. Round each dimension to the nearest foot. Multiply the height times the width of each wall to calculate each wall's area in square feet. Add the areas of the walls to calculate the total area of the walls in the room. Do not subtract the areas of the doors and windows.

Coverage

• Read the manufacturer's usage instructions to find the number of square feet you can expect the paint to cover. Divide the area of the room's walls by the stated coverage area, listed on the paint container, to determine how many quarts of paint you need for the job. For example: If the area of your walls is 700 sq. ft. and one quart container of paint will cover 200 sq. ft., divide 700 by 200, then round the quotient up to the next whole number. Since 700 divided by 200 equals 3.5, the job should require approximately 4 quarts of paint.

Surface Porosity

• Walls that are not properly prepared may require additional paint for satisfactory paint coverage and durability. For effective paint adhesion and even coverage, most walls require a coat of primer. Applying primer prior to painting the wall seals the surface, making the painting surface less porous. Primer also covers marks and stains and helps the paint adhere to the wall.

Color and Value

• The color and value (darkness) of the existing wall and the new paint affect the amount of paint needed for satisfactory coverage. Several coats of light paint may be needed to adequately cover a dark wall. Because some paints are less opaque than others, several coats of paint may be needed to cover a wall with color that contrasts with the existing wall paint. For this reason, many professional painters recommend applying tinted primer to the wall before painting. Paint and home-improvement stores typically offer primer-tinting service, free of charge.