Calculating paint for your room doesn’t have to be a guessing game. With a little measuring and a little math, you can correctly determine how much paint you will need to paint your room. Here are instructions on how to calculate paint you need for a room.

Measure the walls of the room. Measure the height of the room and the length of each wall. Transfer your drawings to paper. The ehow article, “How to Measure a Room for Decorating” gives detailed instructions on how to measure the walls of your room.

Multiply the length and width of each wall to calculate the square footage for the wall.

Subtract the area of windows and doors. Measure the length and width of each window and door. Multiply these numbers to determine the square footage of the windows. Subtract the square footage number of each window to determine how much of the wall you will need to paint. Add the actual square footage that you need to paint of each wall to determine the complete wall surface of the room.

Determine the wall coverage of the paint. You will find this information on the can of paint you plan to buy. A typical gallon of interior paint is 350-400 square foot.

Decide if the room needs extra coats of paint. If the walls have stains that cannot be covered, or if the walls have dark paint, you may want to double your amount of paint to ensure good coverage. A better option is to purchase tinted primer to use as your first coat of paint.

Calculate how many gallons are needed to cover the walls of your room. Divide the combined square footage of your walls by the number of gallons a can of paint will cover. This will tell you how many gallons of paint you need to paint the room.

Dulux have a very good calculator to help you work out just how much paint you may need here.