How to Estimate How Much Paint to Buy

In order to make your painting estimate as accurate as possible and to avoid mistakes and confusions, you will need to make a list of all the rooms or locations that you need to paint and under each room or location, list all the walls, ceilings, and doors that that needs to be painted.

On top of your paper and beside the list of items that needs to be painted, provide three columns for measurements, square feet, and color. This is because for each item in your list, you will need to get the measurement and the area in square feet plus indicate the color you want to apply.

Using inches, measure each ceiling, wall, and door in your list. For a ceiling, you will need to measure the length and the width. For the walls and doors, measure the height and the width only. Please remember to make all measurements in inches and to record your measurements in the list that you had made in step 2 above.

Next step in your painting estimate is to get the size of each item in square feet. Simply multiply the length by the width (for a ceiling) or the height by the width (for doors or walls) and then divide the result by 144. The resulting figure will be the size of each item in terms of square feet. Record your answers under the "Square Feet" column.

In case you will need to apply different colors, indicate the color that you want under the "Color" column.

To come up with the final area size or sizes in square feet, just add up all the figures (square feet per item) under the "Square Feet" column. If you only need to use one color, simply add up all the figures. In case you need more than one color, group the figures on a per color basis and simply add all the figures under each color group to arrive at the total square footage per color. Either way, you will come up with the total square footage per color of all the walls, ceilings, and doors that need to be painted.

Finally, for smooth walls, divide the total square footage (figures you got in step six above) by 350 (the average square feet covered by a gallon of paint) to get the number of gallons you need per color. If you are painting on textured or rough surfaces, divide the figures by 300 instead of 350.

If you are painting over unpainted drywall or over a darker shade or color, you will need to apply primer paint before you can apply the actual finishing color. To estimate how much primer paint to buy, add up all the square feet of the areas that needs to be applied with primer and then divide the figures by 200 (the average square feet covered by a gallon of primer. The resulting figure would give you the number of gallons of primer paint needed.