Determine How Much Exterior Paint to Buy

It's important to purchase enough paint to complete your project, without having a large amount of product leftover.

For Best Results:

BEHR paints are available in quarts for painting a small area, and five-gallon pails for a very large area.

Determine the number of coats it will take to cover your existing surface.

Don't forget -- there's a handy paint calculator at for easy calculations.

  1. image of 1 gallon of BEHR MARQUEE Interior Matte

    Step 1

    One gallon of any BEHR paint is enough to cover between 23 to 37 square meters of surface area with one coat.

  2. Close up image of house exterior

    Step 2

    To determine the number of coats your project requires, first examine the surface you'll be painting. A porous, rough, textured or previously unpainted surface will generally require more paint, as will a project that involves a dramatic colour change.

  3. Graphical representation of house exterior

    Step 3

    Estimate the size of the house body by measuring the perimeter of the house. Then, measure the height of the house from the foundation to the roofline, excluding gables. Multiply the perimeter of the home by the height.

  4. Thumbnail image of sketch of house exterior

    Step 4

    If you have gables, multiply the width of the gable by its height, and divide by two. Do this for each gable and add the total to the body measurement.

  5. Close-up of window trim

    Step 5

    To estimate the amount of paint you'll need for the trim, estimate the length of total trim. The average trim width is 15 cm. Multiply the total trim length by 0.04 meter.  To estimate the gutter, determine the total length of the gutter.  One linear foot of gutter approximates one square foot.

  6. Close up image of house exterior

    Step 6

    Once you add the trim and gutter calculations together, you'll know the additional paint you'll need for them. For doors, multiply the width by the height to determine the number of square meters.

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