Support: Paint Calculator

Tell us what happened. Include which page you were on and what you expected to see. Most answers go out within a business day.

Common questions

How much paint do I need for a 12 by 12 room?

With 8-foot walls, one door and two windows, there are about 333 square feet of wall. Two coats at 350 square feet a gallon need 1.9 gallons, so buy 2 gallons. Painting the ceiling as well adds 144 square feet a coat, about another gallon for two coats.

How many square feet does a gallon of paint cover?

Most interior paints say 350 to 400 square feet a gallon on a smooth, primed wall. Rough, textured or porous surfaces take more paint, so allow 250 to 300 square feet a gallon there. The figure on your can is the one to use.

How do I calculate the wall area of a room?

Add the length and width, double it to get the distance around the room, and multiply by the wall height. Then take away about 21 square feet for each door and 15 for each window.

Do I need two coats of paint?

Usually, yes. One coat often looks patchy, especially over a different colour. Two coats give an even finish; a dark colour over a light one, or the other way round, may need a primer or a third coat.

How much primer do I need?

One coat over the same area. Primer usually covers 200 to 300 square feet a gallon, less than paint, because it soaks into bare surfaces. Tick Add one coat of primer and type the coverage from its can.

How much paint do I need for the outside of a house?

Choose Wall by wall and type each side of the house as its width and height, plus the doors and windows. Rough siding and stucco take more paint, so use a lower coverage, such as 250 to 300 square feet a gallon.

Is anything sent anywhere?

No. The sums run in your browser and nothing you type is sent to us or stored.