I am Painting My Room, How Much Paint Do I Need?

Although painting the interior of your house could be a lot of fun, there are good painting companies that can do the job better and quicker. Hiring residential painters will save you the hassle and fuss of prep work and cleaning up the post-painting mess and muss. Learning a few tips about painting can help you easily determine how much paint you need. A correct estimate of the amount needed will save you a lot of time and money!

Residential painters use a formula to accurately figure out the amount of paint they need for a job. Fear not—it’s not a complicated calculation.

Are you ready for your first lesson on house painting?

Just follow these three easy steps:

Step 1. Add together the length of all the walls and multiply the result by the height of the room from floor to ceiling. What you’ll get is the room’s total area in square feet.
Step 2. Next, figure out the paintable surface of the room area. You need to do this because you’ll be using a different paint for the walls and doors. To determine the paintable area, just subtract 20 square feet for each door and 15 square feet for each window in the room. The number you get after the subtraction is the paintable area.
Step 3. Finally, divide the total paintable area by 350. The result is the number of gallons you’ll need to cover the paintable area. Just double the number of gallons if you want to apply two coats of paint.

I know what you’re asking: Why 350? Normally, one gallon of paint covers 350 square feet. By dividing the paintable area by 350, you get the number of gallons required to cover the interior. Most painting companies use slightly more paint for unfinished walls because such surfaces absorb more paint compared to interior areas that already have a primer.

Let’s work on a sample:

Let’s say the interior area has a total length of 160 feet and a width of 7 feet. It has 2 doors and 2 windows.
Step 1. 160 x 7 = 1,120
Step 2. 1,120 – 40 (two doors) – 30 (2 windows) = 1,050 sq. ft. of paintable area
Step 3. 1,050 sq. feet / 350 = 3 gallons

For this example, you’d need 3 gallons of paint to cover an area of 1,050 sq. feet.

By the way, the formula for painting a ceiling is even simpler, since it doesn’t have doors and windows. You can easily get the paintable area by multiplying the length and width of the ceiling, and dividing the result by 350.

Whether you decide to do the interior painting yourself or have the job done by one of the competent painting companies in your area, determining the right amount of paint is key to a successful and hassle- free house painting project—not to mention more economical!

Vancouver painter and contractor Peter Byrne“PETER BYRNE is the owner and hands-on manager of Kassel Painting Limited. In the last two decades he has run over 1500 painting projects totalling $5.5M. There is little that can go right (or wrong) on a job-site he has not seen, solved, and lived to talk about.”

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